One, that’s not quite true. Sometimes the Constitution uses broad language. For example, the Commerce Clause is worded expansively. It’s probably been pushed a bit beyond the text, but the bigger impact is from vastly more activity in the country involving “interstate commerce.” Regardless, that’s well within the scope of interpretation and judgment.
By contrast, there are a number of things the Supreme Court has simply made up. Conjuring a “right to privacy” from “penumbras” of the other amendments is an example. The “reasonable expectation of privacy” formulation of the 4th amendment. The “wall of separation” of church and state. The country wouldn’t fall into the ocean without these things.
The administrative state is probably the most unconstitutional thing that’s simultaneously necessary. Specifically, regulatory agencies in the executive branch that combine legislative and judicial functions. (E.g. having the ability to promulgate rules and then adjudicate violations.) But one can imagine workarounds. E.g. executive agencies propose rules which Congress enacts. (Proposing laws is actually a function of the executive branch.)
