Apologies if this is already in one of the related topics:
AMO Add to Collection | Userstyles.org
It’s certainly easier to use than the collections interface to collections ;-)
and but I don’t imagine that the style adaptation will apply when the new interface to AMO goes live, let’s see what happens.
Parallel to all of that: re: https://github.com/mozilla/addons-server/issues/2661#issuecomment-325166185 etc. there are opportunities to make the collections interface easier to use, but feedback in that area is not high on my list of priorities.