I thought there was enough Blade in Trinity myself - the problem with the character is that he's so buttoned up that despite the odd comment from Whistler, there's no real insight into his inner motives (not since the original movie tried anyway) which makes him rather two dimensional.
At least other heroes (Bruce Wayne) have complex alter egos and histories which make them who they are.
Watching him kick butt in the first two was cool, but by the third it was clear there was little more to him which made him seem a bit flat compared to the other characters.