I hate that we didn't see him much. Hard to say how he could have been incorporated more in the story, but I feel that there could have been more. In any case, I really am not bothered by him.
Exactly this, Vanitas had way more potential that was wasted during the game.
His appearance doesn't bother me at all and the
idea behind his existence is very good...it was however clearly not executed well.
On that part I agree, he should have been way more involved in the plot and let the audience
see and
feel his evil. Him tormenting Ven for two times at most was a beginning but certainly not enough.
Or, as a friend of mine would say:
Idea and Concept: Good!, Execution: FAIL!