To use a gaming term, I'd say She-Ra's powers are broken. With that Silly Putty sword of hers, a flying steed, healing powers, telepathic links with most if not all of the animals of Whispering Woods and access to two castles that contain great power, she probably didn't even need He-Man half of the time he showed up. Yes, She-Ra does have a very rich background and went through more than Adam did growing up. Personally, I'd like to think she was brainwashed instead of being tricked by Shadow Weaver.
As far as stuff like that goes, I'd look at He-Man like a blank slate. He's ready to have a mell of a hess dumped in his lap. He's got the potential to fall from grace and have the audience feel much more sympathy for him than She-Ra would. I only say that because of her ties to the Horde even if they weren't intentional. As far as them being unbeatable, that'd be too predictable and become very old very quick. If the Council of Evil, the Horde and the Snake Men all organized their efforts; they should be able to give the Grayskull Twins a run for their money. Albeit enough of a run where they'd need the Sorceress and maybe some help from Light Hope or Teela (with her Warrior Goddess powers realized) to bail them out.