Dr. Midnight did come on pretty strong. Perhaps I can re-state at least part of his position in a more reasonable way....
When I was a kid, my Mom had a rule - at mealtime, if I saw something new on my plate, I wasn't allowed to reject it until I had at least tried a few mouthfuls. After I had tried it, then I was allowed to make my own judgement, and if I didn't like a thing, my Mom would make an effort to accommodate my tastes. That was cooperation.
Yes, the game is cooperative, but that doesn't mean the DM must allow any character the player wants. Cooperation is a
two-way street. Sometimes the player needs to take what the DM wants, sometimes the DM has to flex for the player. A player who insists on having his own way too often, and pitching fits when he or she is told "No", is not being cooperative. Similarly, the DM that refuses to flex at all for a player isn't being very cooperative either.
It really wouldn't be fair to the DM to reject his pre-generated character before seeing it, and hearing the setting, and playing a session or two. I'm glad to hear that ForceUser has heard the DM out, and is willing to give it a try. That's being cooperative.
To put a bit of a counterpoint to Kid Charlemagne - I actually have seen such pre-generation used before, with wonderful results. When done properly, it actually helps generate creativity, rather than squeezing off the flow. Kind of like a poet who normally only works in free verse deciding for a while to write only sonnets, to see what something else is like. Usually, when he goes back to free verse, it's with some new wisdom...
Players have habits, and sometimes games can get a bit boring if you always allow them to stick to their habits. Giving them a pre-gen can break them out of ruts, and shake them out of creative complacency. Give it a chance, and see how you like it.