He was rendered with less detail than a CG character that had more time given for completion. I assume he was a rush to last minute change. I'm also assuming in the next film he'll get the time and effort that is needed to make him more convincing (added detail).
Neither did I, I was just surprised how rubbery his skin looked and the scars on his face lacked detail, he looked like a rushed job.
We might see Bolg in the next movie, his absence in these films hasn't been ruled out yet. He's in the promotional material for movie one before the films were split into three movies. It's rumored that he'll be in movie two and he'll be in the battle of Dol Guldur as you can see in this promotional picture.
Here he is on the Dol Guldur set.
http://heirsofdurin.files.wordpress.com/2012/02/bolg-son-of-azog-hobbit2.jpg