Show me the Constitutional authority for them. Have you got any idea how much tax revenue they deprive the states of? Honestly I would have no problem amending the Constitution to allow for the National Parks, but there is no reason to have all the national forest, wilderness areas, grass lands and other areas that serve no compelling national interest. Are you aware that the federal government own or controls almost 60% of the state of Utah?
Article I, Section 8 of the Constitution declares that “The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defense
and general Welfare of the United States.” A national park system, which is part of the “provision” for the “general Welfare of the United States,” and therefore fits perfectly well within the constitutional authority of the Congress.
The courts have interpreted the general welfare to include a multitude of federal services including parks and monuments. One can not expect the founders to specify in detail all actions of the government hundreds of years in the future.