I don't like these kinds of user-visible changes, because if someone liked the old behavior, or was at least accustomed to it, they now have to do research and become involved in ASDF to learn how to get the previous behavior.
i don't really have an opinion on the specific topic, and i don't mean to annoy...
but what if someone *didn't* like the behavior? then they would have to do research and become involved in ASDF to learn how to get rid of the current behavior (notice the almost exact same wording of a counter argument).
just pointing out that to me it seems like you're simply stating your personal preferences and/or dislike for change. it's a common human behavior and there's nothing wrong with that, especially in your case Zach: as author of quicklisp you obviously try to minimize headaches caused by changes to ASDF. but if this really is the case then we should be aware of that because it often hiders technical discussions and development of software systems (the closest example that comes to my mind is what is happening to Slime. or really, what is *not* happening to it...)
the ultimate backwards compatibility is not having had even started the project in question (modulo my english grammar deficiencies).
also worth noting that people much-much more often speak up of annoyance than being pleased by a change.
</rant>