Certainly, "enough" is doing a lot of work and things get blurry, but I think "good enough" is meant to capture some of that. Over building is also a problem. It isn't strictly true that building longer lived things is cheaper over time either, it obviously depends on the specific things getting compared. And if you go 100 years rather than 25 years, you'll have fewer chances to adjust and optimize for changes to the context, new technology, changing goals, or more efficient (including cost saving) methods.

Obviously, there's a way to do both poorly too. We can make expensive things that don't last. I think a large chunk of gripes about things that don't last are really about (1) not getting the upside of the tradeoff, cheaper (in both senses) more flexible solutions, and (2) just getting bad quality period.