But this is what I've noticed about the difference between his mainstream and his own stuff. Please bare with this analogy.
It's like if he took over Sweethearts and decided to eliminate all the flavors and change them with: Coffee, pumpkin pie, sardine, and lasagna flavor. Then turns around and makes his own brand of sweethearts with grape, cherry, orange, and lime flavor.
I don't get why he does that.
See the one thing I really like about Morrison is that his stuff is always his. ASS, New X-Men, Batman, Seaguy, Final Crisis... he does it his way. I absolutely love his Batman although I think RIP is clumsy. I like the ideas of FC but hate the execution. New X-Men is the only run of mutant books besides X-Factor that I like. He isn't afraid to do things and for whatever reason editorial lets him have a free hand. It makes his books exciting, you never know what is gonna happen.
Then you take someone like Hickman who had a brave, new voice at Image only to be neutered when he came to Marvel. Sure he is better than the other people that have written FF for a while and Secret Warriors is awesome, but they don't feel like his previous work. I have the same problem with Remender (outside of Frakencastle) and Fraction to an extent (although he has become a better writer, if a weaker voice).
Morrison isn't afraid to try things. Sometimes he fails (Final Crisis), sometimes it is clumsy but admirable (Batman), sometimes it is brilliant (All Star Superman)... but it is always interesting and new.
Pull list: Afterlife with Archie, Bodies, Chilling Adventures of Sabrina, Coffin Hill, Dead Boy Detectives, The Fade Out, The Goon, Harley Quinn, Hinterkind, Iron Fist: The Living Weapon,The Maxx Maximized, Miracleman, Ms. Marvel, Multiversity, Rasputin, Rocket Raccoon, Sandman: Overture, Silver Surfer, The Walking Dead, Wonder Woman