Frankly, I've hated the band ever since he came back anyway. His playing has been weak ever since he dropped out the first time from excessive heroin abuse (so it's not like this the first time he left, and declaring the band dead may be premature). If the band could write a single song that didn't focus on how evil california is, it would be a helpful start. I know that the others didn't get along well with Dave Navarro, but I'll take just about any track on One Hot Minute, over anything that followed.
As for Flea, his playing was a lot funkier back on Albums like Freaky Styley. As he's gotten older, he's said in interviews that he isn't as interested in showing off with his playing. Well, that might be helpful from time to time.