JMW: Sigh, I'm very glad you asked this question. The idea to make Gamma World wackier was not mine. It came from several designers from the TSR staff. On the other hand, I never considered a 9-foot tall humanoid rabbit that could turn all metal into rubber—wacky. This might be an area where I have blinders. I went along with the wacky material because I had lots of other things to do in those days. In hindsight, I should have used some editorial brakes on some of that material.
I could not agree more.
Ward's interesting interview is here. He's got a great perspective on the early days of roleplaying. It's really worth a look.
And I have to admit, it's nice when the game designer vindicates my decision to put the seriousness back into Gamma World.