Why is Johnny Marr still playing with Modest Mouse?

That is a question that plagued me for the last few months. Initially, I wondered what affect he would have on the band's sound. The answer: not much if anything. Marr, 44, is the former guitarist for the new wave band "The Smiths." Brock said he was at the top of his list to replace outgoing guitarist Dann Galucci, so he called, Marr said yes and they've been producing quizzical, banal contemporary rock and lackluster performances together since.
When closely studied, with a keen ear, nothing - I repeat - nothing Marr does stands out on record "We were dead before the ship even sank" or live "St. Paul xcel Center, June 5." Literally. The dude is there probably as a mentor and as a draw. Sounds like fun, but I keep expecting the experiment to end. It hasn't and there's no indication it will anytime soon.
He's not an outstanding guitarist, in my very humble opinion, but is a nice guy. I can understand why they like him, and why they'd pimp him for the freak show aspect of Marr joining the Mouse and therefore making the band a SuperGroup. I have to tell you, my loyal readers, that never in the history of SuperGroups, has it improved anyones sounds collectively or individually (see, most recently, Velvet Revolver; or the Plastic Ono Band if you wanna get real ol' school). It just don't work.
The Mouse's key components, its core: Brock on guitar, vocals; Eric Judy on bass and Jeremiah Green on drums is where the band draws its strength. I've seen bands add more members time and time again and I find it only weakens the potion. So go figure. Why is this continuing? Why is he still here? He's nearly a grandpa for St. Christoper's sake.