Originally Posted by The Overlord
Mole Man doesn't have to be "extremely" compelling, but he has to be somewhat compelling, he can't be a generic bad guy and carry a movie. Plus they can build up Dr. Doom as a threat in the back ground in this movie, so when he does appear, it will be really exciting because of plot points about the growing threat of Dr. Doom will come to a head, like what they are doing with Mandarin in the Iron Man movies.
Besides the fact that we got a goofy version of Two-Face in Batman Forever and a really lame version of Bane in Batman and Robin, didn't change the fact they got an awesome Two-Face in Dark Knight and an awesome version of Bane in Dark Knight Rises. McMahon hasn't ruined Doom forever, if we see an awesome version of Doom on the screen, people will forget about the McMahon Doom.
I'm not just talking about how he's written though. What if they get a really good actor to play him, and he brings out a brilliant performance, much like people are praising Ben Kingsley, or have done for Heath Ledger? The actor could turn him into a classic movie villain, and then he'll essentially become the General Zod of the FF franchise where the general audience thinks he's either Superman's only real nememis or arch enemy (not helped by MoS).
For Doom they would need to get a really seasoned and oscar winning actor this time - someone older too. Definitely not a second rate tv actor that's for sure. I remember when McMahon's name was in the hat for James Bond when Pierce Brosnan was being fired from his role and before Daniel Craig had been cast. I think he was once on Leno (or some similar show) and did his "Bond, James Bond" impression, and it sounded awful.