sorry Stas, but i just had to dishonestly (?) cut your mail... :) with the hope that it will incite some reflection:
I specifically don't update cl-ppcre.asd [...]
[...] and all the users can do is just to suck it up.
FTR, there's an open PR with discussion: https://github.com/edicl/cl-ppcre/pull/30
i understand that "it was him who made the first change!", and "everything would still be fine if he doesn't make a change!"... but i'm not sure it's reasonable to expect this kind of conservatism in a collaborative space. old ASDF was a piece of software that wasn't designed for the tasks it is used for today (as in its API, let alone its implementation), and that was causing a lot of headache to "the users" you seem to be defending above.
i don't have a strong opinion about this specific warning. to be honest, if i was the ASDF maintainer, it would be fine for me if the warning was off by default, and i would only turn it on in my own CI to send out the PR's and/or warnings to the relevant maintainers, and then let old and/or conservative libs continue to misbehave as they did with the old ASDF.
but it's quite disheartening to see all the trash-talk against the refactored ASDF. i may be just one user, but the cleanup of ASDF helped me tremendously! maybe i was using more deps than usual (~100), and had to deal with live systems and whatnot that most CL users don't do...? but prior to the ASDF cleanup i had wasted countless hours hunting build-related bugs only to realize that there wasn't any bug (in my code), and by getting used to mindlessly rebuilding from scratch *any time* something strange happened.
conservatism, and the general hostility, has always troubled me in the CL community, but i don't have a dog in this fight currently, or maybe even anymore, so i better cut the talk...
good luck resolving whatever needs to be resolved for a better tomorrow!