I think we're all intelligent enough here to know that just because someone is a great musician, doesn't necessarily mean they are great songwriters, or vice versa. But this doesn't apply in Extreme's case. Cherone/Bettencourt obviously are a great songwriting team, Bettencourt is a virtuoso musician, and Cherone one of the most gifted vocalists in hard rock.
So none of that really applies in this case. Clearly, they don't NEED help. They CHOSE to have help. And that is the question I'd like for someone to ask them and get an answer to, that is more than just a soundbyte.
As for a band writing its own music, yes, I for one think it is vitally important, particularly in the hard rock/metal genre. Pop music is wonderful, and there are a lot of talented songwriters who write for gifted pop performers and artists. But rock/metal is, and should be, IMO, different. To be honest, I respect someone like Adele, Pink, or even Taylor Swift, who all write their own songs (so I am told), a lot more than an artist who literally is on stage performing songs written by everyone BUT them. To me, that separates the hard rock/metal genre from much of pop. That doesn't mean there can't be exceptions, but in general, for me personally, I want my hard rock/metal bands writing their own stuff.