The only times Mickey Mouse was ever funny was in the very, very early shorts. He got to be a rebellious, rowdy pipsqueak. Go watch The Barn Dance or Plane Crazy or The Barnyard Battle. Later on they toned Mickey way down and made him a put-upon sweetheart and he just stopped being funny. They were too afraid of…

I think Disney is just very cautious about giving its artists too much creative input, recalling back to feature animation dark ages during the 70's and early 80's