I think one of the reasons why people don't like MOZ is because they were kind of expecting a tribute to the 1939 movie, rather than going closer to the original L. Frank Baum novels. Again, that's just one reason.
I'll agree the songs from MOZ were pretty forgettable, and by that token, the movie also seemed to be something of a vehicle for Ashanti (who, at least, is a big Muppet fan as Jason Segel was, so that kind of helps). I'll also agree that there were moments from the movie that were memorable, as opposed to the movie as a whole. But at least, with the exception of the nipple joke, the forced adult humor was toned down in comparison to VMX. Plus, David Alan Grier, Queen Latifah, and Jeffrey Tambor are always fun.