Hey, guys! I decided to join the discussion after a very long hiatus. Anyway, I actually like the alter egos. I guess I'm just a big sucker for Prince Adam.

But anyhoo... the way I've always viewed it is that the alter egos were a must. Prince Adam simply can't be He-Man all the time, because to him, that's not who he is. He was born Adam, so he wants to be Adam. He-Man is still him, but it's also a job. With that being said, he has to keep his alter ego a secret, because it could bring about a lot of problems. If Skeletor knew the truth, he'd do everything he could to catch Adam before he turns into He-Man. He would make sure to keep the Power Sword away from him. He might even kill him in his Adam form. This is why he's unlike Superman. When he's Clark Kent, he's still invincible, for the most part. This isn't true with Prince Adam. Besides, the existence of He-Man as a separate entity from Prince Adam keeps Skeletor's attention divided. Besides trying to take over Castle Grayskull and taking over Eternos, he also tries to think of ways to outsmart and get rid of He-Man. If he knew He-Man was really Prince Adam, even all of his effort would then turn to Eternos and Adam's family just to get to He-Man. He would do everything he could think of to get at Adam: destroy Eternos, kidnap his family and friends moreso than he already does because his family are who they are. It would never end for the poor boy. And, let's not even mention that if he stayed in He-Man form, he would constantly have to deal with people wanting to hear stories from him or help them do this or that. He'd never have a moment's rest.
As for the alter ego with Adora, I wouldn't think it would make a difference on Etheria for everyone to know, but of course, that would lead to Hordak putting two and two together and discover Adam's secret. And, if the people on Etheria knew, how would they keep it from Eternians since Skeletor keeps an eye on Etheria and Hordak. I'm sure he'd pick up Adora's identity and then put two and two together with Prince Adam. So, even for her, a secret identity is a must.
And, as for Teela, I tend to agree with Blue and the others on this one. Also, let's not forget, if everyone knew she was the future Sorceress, once again, Skeletor would use Teela as leverage against the Sorceress. Sure, he's used her against He-Man, but if he knew the truth, her life would be a lot harder because he'd be after her more often than he already is. And, I don't believe he's ever used her to get to the Sorceress. I honestly think if he used Teela as leverage on the Sorceress, he'd give all the good guys and especially He-Man and the Sorceress a run for their money.
That's just the way I've always looked at it.
