KirbyFan4ever wrote:
Good point, but then Steranko was on Fury about three years before Jack left Marvel, and Colan on Strange about two years before.

I think I heard that Adams did not like working the "Marvel Method" as he felt he was writing as well as drawing and wanted to be compensated accordingly.
Adams has said in interviews that he came to Marvel to work specifically with Stan Lee (and later, Roy Thomas) and when the writing was given over to others, like Gerry Conway, his interest faded and he moved on to other companies (that's why he left X-Men, Inhumans and War Of The Worlds). There also may well be money issues, but I haven't read about them.