Mandrill’s looks aren’t really a problem, but the fact that he uses his pheromones to seduce and control women is.
This ability has allowed him to live a polygamist lifestyle, and he’s used powerful women in the Marvel universe to commit various nefarious deeds.
Mandrill can bend most women to his will provided they catch his scent, and he can even keep them under his spell for months at a time.
Mandrill would be perfect fodder for a Deadpool villain because the plot would have to be silly to prevent people from straight up walking out of the theater at the sheer ridiculousness of this villain.