Keith Richards said it better himself:
"First off, I thought it should've been something that he REALLY wanted to do that he couldn't POSSIBLY do with the Stones. I thought the timing was strange, bringing out something like that, an obviously commercial record, just as we were starting to record this album. I mean, if it'd been his favorite Irish folk songs with a lady harpist - something you couldn't do with the Stones or anybody else, something you've been DYING to do for twenty years and really want to get off your chest - then fine. You know, Liberace accompanying you on Frank Sinatra songs, whatever (laughs). I did talk to him about it, told him it was dumb timing and not an inspired piece of work... To my mind a Mick Jagger solo album should've been GI-NORMOUS, not just another record. I said to Mick at the time, Why don't you leave this year to Prince and Jackson and Springsteen? Cut a few tracks here and there, work at it slowly until it's finished? Why make yourself a deadline when you don't have to?"