Originally Posted by Dark Raven
If they use the Moleman and make him an extremely compelling villain, people are going to think that he is the FF's arch enemy and will keep wanting him back. If they remember Julian McMahon's Doom as well, they'll think he pales in comparison to the Mole Man. Doom will have been castrated and will always be inferior to almost every other comic villain.
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.