[foobar__]

Both Isabelle and Coq are based on higher-order logics, so I am not sure how first-order logic is a barrier to entry. Especially Isabelle is very easy to use because the logic is so standard with nothing really surprising or especially restricting (a very strong form of the axiom of choice is deeply embedded in the system, so it's probably harder if you care about it at this level).

Regarding your second point, to me this looks pretty much the same as in software: In high-quality code I expect high-level comments that give me intuition about the code, and I also expect high-level documentation giving me further intuition about the components and the system as a whole. The more complicated the system is, the more important the comments and the documentation become.

I see no reason why we should hold computer-assisted proofs to a lesser standard.