I always thought of Malak as a bad attempt at doing a Vader character, with his silly ways and dialogues (not to mantion his ridicolous over-the-top apprentice!). I look at KOTOR2's characters as fresh and new, with their own motivations (unlike in KOTOR1), with Kreia probably being the best one in the cast. In the end, I know KOTOR2's darksiders are "overpowered" compared to the OT's, but I say that the balance is kept if you consider that their power is the reason behind their own sudden death, and you could say that Force-users learned from their mistakes since then.