A lot of their issue is they thought Will & Jada's marriage was flawless. Lot of us grew up watching Fresh Prince and all Will's biggest movies. His kids are alternative, dress how they want and act how they want(nothing negative though). So I guess to a lot of these fellows, Will is emasculated and he isn't in control of his household.
Reality, Will is a normal person underneath all the money and successes(Duh). If the marriage was so bad and displeasurable to him, he'd leave already and move on to the next. But I'm sure he's fine in it and a lot of the naysayers don't actually have a successful marriage or family to speak of.