The comments about Mega-Me are interesting. I pretty much feel the same way, although in my dotage I'm still able to deal with the smaller interface. However, I don't switch to Mini-Me because they usually stink. Many years ago I got a player from Adaptec that was bundled with a card, and it had a mini interface that was exceptionally clear (this was Win 3.1, that's how long ago this was); it was the height of the title bar yet had exceptionally clear buttons and track time on it. I used that all the time.
Similarly, I use Sonique's mini-mode all the time because it's very clear and packs an unreal amount of functionality into a few pixels; frankly I still think they're the one to beat for innovative interface. Buttons are clear, they've got rollovers on them, there's track info, search...it's rad. (I notice that the latest MusicMatch also has a small mode that bears more than a passing resemblance to Sonique's.)
None of this happens with most of the other mini-skins. Most of them, although they display nice artistry, have clarity and functionality as an afterthought. I can't tell what I should click on for what, some buttons are just graphics that do nothing, some things look like a button but are bolts or other flourishes, no rollovers...it's a mess more often than not. I'm not sure that WinAmp compatibility in that regard is such a fine thing. Mini-Me ought to have its own engine and its own skins that go beyond what WinAmp can do.
I think some centralized control over user skins isn't so poorly advised either. It seems like it's possible to publish a skin that doesn't even DO jack. I have no idea that a skin only provides the 'play' function and nothing else until after I've screwed with it for ten minutes. It would be nice as a user if before skinning or downloading it, I knew to what extent and what functions the creator had complied with. You know, like if they implemented everything to standard (all functions, every button has rollover states, etc.) they get the MJ logo next to the skin on the download page, or some other notation that indicates that this is a skin that does something besides look like this.
I honestly don't know people who flick between skins on even a daily basis. It seems to me that people find one that is GOOD (and usually good seems to revolve around "works good" first and "looks good" second), and stick with it and that's what sells it. A legion of skins that are bad or compatibility with a host of bad skins isn't doing anything for MJ, dontcha think?