What would you define as "really fat"? He may have gained 10-20 excess lbs, but that's not unusual. As was pointed out before, what he did was really hit the weight room and got huge in his upper body. In that case, he was overtraining, not being casual about it.
I'm wondering if you are also angry at Zach Randolph for gaining even more weight than Oden after he had his knee surgery. They had to put him on that dumbass bike because he was too fat to do any normal rehab. What about Joel Przybilla slipping in the shower and reinjuring his knee?
I think you're angry at GO because he represented the final piece after a long rebuild. We were poised for greatness and it crumbled with Roy's and Oden's knees. I'm disappointed, too. It stings like hell three years later, but I don't blame Oden for it.