I agree that Keith behaves childish sometimes and some of his comments are certainly over the top. But that's the way he is and Mick knows him good enough not to take it too serious. However, there is always some truth in Keith's statements, in my opinion.
I don't know - I still have that feeling that Mick constantly tries to prove that he could be a star on his own... he's recording pop music because probably he thinks that's the way he attracts the most people, he always trying to please.
I'm not saying it's bad music, I like some of his solo stuff, I really like Old Habits Die Hard, especially the duet with Sheryl.
But that's not the real Mick for me, it seems like he tries to present himself as a person he isn't. He is the frontman of the greatest Rock n'Roll band in the world, he doesn't have to prove anything, and it can't get any better anyway!
And I think Keith's comments are very useful to bring him back where he belongs - to the Rolling Stones. That's where he really shines, with them he is a star!