I started moving away from YUI between v2 and v3, mostly because the project started feeling very disorganized. There wasn't a clear timeline as to when components from v2 would be upgraded to v3. Namespacing helped, but I didn't want to invest time developing code around v2 components if v3 versions were right around the corner, but there was little to no insight as to if/when components would be migrated.
That seems to mirror the rest of Yahoo from what I've seen - some really good/cool/useful tech, poor management/communication about it. Perhaps at that size, it's just endemic in a culture?
YUI 2 was an awful mess but YUI 3 is pretty good. YUI 3 actually came out a while ago (it's at version 3.4 I think). But it's gotten a lot more simpler thanks in part to mimicking jQuery selectors.
That seems to mirror the rest of Yahoo from what I've seen - some really good/cool/useful tech, poor management/communication about it. Perhaps at that size, it's just endemic in a culture?