I agree, Rick B.  Another way to put it:
 
National Parks unlock these places, allowing the resources to be enjoyed and valued as something other than commodities. 

Several needed clarifications:
A.  'Executive Fiat' from Anonymous #1:  wrong on many levels.  "Fiat" is a deliberately chosen perjoritive word which is the unrestrained act of a dictator.  "Presidential Proclamation" is authority duly authorized by Congress more than 100 years ago, an authority that has stood up to multiple challenges and calculated outbursts.  Elected presidents are authorized to carry out the will of the elected congress in laws; that is what laws do. That is NOT 'fiat.'  More to the point, Annonymous 1, while trying to score points made the typical such mistake of getting his facts wrong.  One of the two was authorized by an Act of Congress, NOT established by executive proclamation.  All the Executive did here was certify as the law required, that the park could not start up until the City was in agreement.  The other park,  Ft. Monroe, was already owned by the United States and this is just a jurisdictional change, and overall the United States saved money by shutting down the military base and retaining only the new park (aka- National Monument).  Not only that, but far from a 'fiat,' there was  complete bi-partisan and local support asking for the President to proclaim the national monument.  The local Republican congressman AND the pro-Tea Party Republican Governor both asked the President to use his authority to make the proclamation.
Anonymous #1, a question:  after the Earthquake in VA the same governor also asked the President to declare an emergency and provide federal funding; the governor complained when the President did not.  When the President declares an emergency, have you objected in the past that this is a "fiat?"  Or, was it a "fiat" when the President turned down the Governor's request for declaration of FEMA emergency?  How would you distinguish your opinion about one, from your opinion of the other? 
B.  On several comments on the costs of "lock up," incl. Anonomous #1: Again, it always is important to actually  know the facts, area by area, rather than argue from ideology.  Neither of these historic parks are subject to any realistic development, other than preservation development.  The Great Falls  in Paterson has an existing, historic, productive hydro electric site that will still continue within the park boundary.  All the other lands immediately around the Falls are park land.  All the lands within the boundary are both an existing National Historic Landmark, AND a National Natural Landmark.  National Park or not, any development plan would require federal funding and no plan could be approved that  was inconsistent with preserving the historic  resources.
C.  Anonymous #2 "pay as you go and leave those without interest in the way the Parks are managed, alone and not required to fund operations that they have no say in. . "  Again,  another huge wrong comment on how the United States works.  Again, the congress and the President who authorize parks are all elected,  and  hugely influenced by public advocacy.  The NPS conducts elaborate public comment opportunites on new parks including these two new parks before establishment, where all substantive comments are noted and addressed; once parks are established, within the scope of the purposes of the law, plans often are modified based on public input.  Plus, year in and year out, communities are directly engaged in influencing funding for each park, and the public even gets involved in approval of the park fees.  No development can even happen in any park without another round of public participation.   It is silly to say they have no say in what happens at every step of the way.  What would be your motive for asserting it?
D.  On the funding comment of many, again it is distorted to say older parks lose because new parks are established.  (except perhaps in the first year of their establishment or congressional earmark)  Overall, the NPS budget goes  up faster than the new costs.   The new costs are tiny  compared to the whole.  Assuming from experience that the most these parks will get before their General Management Plans are done many years from now, will be about $1 M for operating the parks.  By that estimate, for every $2,300 that goes to park operations, only ONE dollar will be made available for these parks together, and it will not come out of funds for the older parks.
Existing park budgets are not hurt by creating new parks.  What hurts the budgets for parks are uncompensated cost of  living increases to employees or purchasing, and most especially, huge amounts of paperwork for "accountability" programs that have next to nothing to do with actual accountability, but cost staff time and attention from actually protecting parks and providing for the visitor experience.
In short these parks will pay for themselves, bring needed national recognition, broaden the base of supporters to parks in regions far away from the large Western national parks, enjoy strong and bipartisan support from both the private and public sector, and tell crucial stories of the American experience that are told at no other  national parks now.
 
 
 
 

d-2 -- an excellent and sensible reply.  But sensible answers and facts are no match for ideology.

Gee, Anon 1, think about this. In my own state of New Mexico, using the authorities of the Antiquities Act, which was signed into law in 1906 by President Theodore Roosevelt, six Republican and four Democratic presidents have designated 10 national monuments: Aztec Ruins, Bandelier, Capulin Volcano, Carlsbad Caverns, Chaco Canyon, El Morro, Gila Cliff Dwellings, Kasha-Katuwe Tent Rocks, Salinas Pueblo Missions, and White Sands. Two of these areas - Carlsbad Caverns and Chaco Canyon - were later re-designated by Congress as national parks. We would be much poorer in spirit if these places had not been placed in public ownership. That's right, they belong to the people of the United States and I am one of the proud owners. So should you be. As usual, d-2 has it right.

Rick

Back to the original question: it does seem unwise to be creating new financial liabilities when we are not sure how to support the existing parks.

But on the other hand, if we don't preserve them now, when will we?

And on the other hand, how do we determine which are really worthy of park status and which are political pork?

Where is Solomon when you need him?

-- a sustainable strategy SHOULD be a factor in considering new parks, especially in urban areas or in the midst of places people live. 
-- These days, non-profit foundations don't undertake any bold new initiative unless they build an endowment right into the fundraising plan.  In a way, the same needs to be true for new parks, again especially those in the middle of a larger cultural landscape.  You need partners with a long term incentive to want to support the park, and who see the success of the park as essential to the success of their community.  You need interpretive themes and a General Management Plan broad enough to engage the excitement of the community that the park really speaks to them and what makes America important. 
-- You need some sort of concept going into the legislative process that gives you the long term framework for the costs of development.  Under current NPS guidelines, those costs must be appropriate and manageable, and the cost of the long term operation of those facilities must be afordable and evaluated.  You cannot be building huge Visitor Centers with no revenue streams, because if you do all your operation costs will go to turning on the lights and staffing that VC, and you will neglect the protection and visitor experience of the prime park resources themselves: the park operation will become a visitor center operation.
-- If you keep these things in mind, new parks are affordable, and do not hurt existing park operations beyond the first year or so.  It is simply not  true that it is a pure zero-sum game, that every new park takes money away from the existing parks.  But it is true that you need a strategy.  The NPS originally opposed the creation of the Paterson Great Falls  because of doubts that the community was not on the team.  IE:  not part of the endowment.  Now, it looks like the NPS officials feel they have enough community support to 'establish' that new park.   The point i am trying to make is, yes, we need to be smart and strategic in establishing and operating new parks, but we cannot abandon the job of protecting  America's most important places because opponents of environmental protection exploit budgetary fears to put a stake through the heart of good preservation strategies.