Different social media spaces have different norms. You may not be able to describe them, but you sure can feel them. Finding the space the clicks with you is often tricky, just as finding a voice in a new setting can be. This is not to say that one space is better than the other. I don’t believe that at all. But I do believe that Facebook and Twitter are actually quite culturally distinct and that trying to create features to bridge them won’t actually resolve the cultural differences.