Maybe it is wanted that way? Can't let every compainion being the same. Comparing Astarion and gale is like comparing apples and pears. I find Gale rather funny, but if you're into drama and the dark side of the game, you may better stick with Astarion instead of judging other companions.

How can a romance be more evil than Astarion's? If you want evil, if let him acends and become his spawn. I romanced all the male companions at least once each. So i can safely say. Astarion has the best written story already. I think the other companions need the improvement more than him.