I traded for him. I gave up the 59th pick which ended up being Trevor Ariza. I agree a better guy on defense would go a long way but there are few better fits in offense.
Having 5 guys on offense that can create for themselves, shoot, and pass would be a matchup nightmare. Those pick rolls would be hard to stop.
Plus Griffin is pretty solid on defense of smaller guys. He can stay on a guy for short stunts on switche. This let's me switch on every screen and have length on everyone. A run protector would be nice but that's easy to counter. It's easy to pull centers away. It's not easy when a team can switch every where has 2 elite defenders on the court.