Except that Reed Richards isn't Lancelot...
What do you mean "stand up to Sue"? When would he have needed to stand up to Sue, exactly? I recall him being basically unaware of relationship norms when he was scientifically fascinated with something, IE, overlooking Sue and her feelings for him and her desire for him to step up and make a move, but I don't remember him, at any point, actually being an "emasculated wimp" or failing to stand up for himself. Not in any real sense.
And I recall him standing up to Doom several times. Just because he had to go to Doom for help at the beginning of the film doesn't make him a wimp. It's more about that being a story gymnastic to get Doom into the storyline as a part of the Four's origins, and to reveal their past together, etc, in one fell swoop given the runtime limitations.