The problem is not Grant Morrison. The problem is Grant Morrison having been given a blank cheque. He has created some positively compelling comics over the years--the Coyote Gospel from Animal Man, much of All-Star Superman, and parts of his run on New X-Men were astonishing. The problem is that most of his past work has been much more tightly focused (if sprawling within those bounds). He just
gets Superman to play with, he just
gets a small team of X-Men. Final Crisis gave him an entire universe to play with, and, from the sounds of it, he wanted to fit every toy he had or knew of into one story, and his considerable energy went to naught.