i can't imagine michael mcdonald ever being well-liked outside madtv
No offense to whether he's a likeable guy in real-life but most of the characters he creates are not endearing. They're crude and offputting. The one that comes closest for me, to being likeable was Rusty.
I don't think McDonald got that characters need to be likeable or have something to root for in comedy if they're the center of the sketch. His cynical retarded character who turned out to be the meanest guy in the room if you weren't so empathetic towards his being retarded was almost offensive.
I think McDonald's characters were a key to the difference between Mad TV and other venues of comedy. Mad TV's style was a little cruder and therefore McDonald could thrive there but i don't think McDonald would ahve too much success elsewhere. I don't think Stuart or the depressed Persian tow truck driver or any of his other characters would be anywhere close to enjoyable to watch in a movie or tv show