The problem is most people who end up using autotools and other build/install/package tools are not interested in their internals or interested in working on them. They just want a tool that gets their job done and they get to do something else.

I realized this a while back, when I was advocating git at my company (maybe 5 or so years back...) some developers loved because they like the idea of it, they wanted to know how it works underneath etc., other group didn't care, didn't want to hear about internal they just wanted a list of commands to type to get their code committed.

Neither one is wrong or or bad, it just comes down to personalities or interests. Autotools is a bit in the same area.

A lot of people will complain about it, because they want to use it to get stuff done. But they will never the ones to start writing tools like it, because they do something else -- databases, graphics, numerical simulations etc.

So "start working on a successor if you don't like it" might not have the same effect for this project.