I've been thinking about that. As egotistical, vain, obnoxious as he is, I do think Charlie Sheen made the show. I don't think he can be replaced. It's about the only show that makes me LOL.
I feel awful for the other cast members too. I think I read that Sheen knows his lines and arrives on time etc. He just doesn't know when to keep his big mouth shut. He made a cruel remark on the radio about the creators first name too, which added a gazillion more points downward on my Sheen ladder.