Aaron L said:
What is wrong with munchkins? If they're in your game and making it less fun for you, then I can see a problem. But if somebody, somewhere, wants to play a game of D&D just to get powerful characters and do crazy things they never could in real life, what's the problem? Almost everyone starts out in RPGs as a munchkin. Some people develop different tastes, and some don't. If they are having fun, it isn't hurting me.
Maybe not directly. However, it can poison the player pool. Lets so someone hears about 3e, has been out of the game for a while, and wants to try it again, and starts up with a munchkin group. After realziing that said group plays a virtual arcade game, they quit and are convinced that "3e is for muchkins." They may quit RPGing entirely, or they may go onto other RPGs and become a d20 basher.
Also, there is a good chance that you might have to hammer together a group with some players who learned to play that way. Playing munchkin in a normal group is a recipe for disaster, or at the very least severe GM headaches.
Let me tell you a story about a potential player that got involved in my group recently. We'll call him Jerry since that's his name.
Jerry knew one of my players and asked to join. He had never played 3e. He wanted to play his old 2e characters (alarm bells! Player who only plays one characer!) His character was a member of a munched out 2e specialty priest class that was like the one in F&A for Tempus but more powerful. (Alarm 2: FR. Alarm 3: Self made classes.)
I had to explain to Jerry that my world was not FR in any way, and that the best we could do is to try to work up an equivalent concept in my game world. It was a tough fit, but eventually I worked up a prestige class that was a weaker version of his.
He still kept trying to use his old characters abilities. What's worse is that he was openly demanding of the other characters and had a superiority complex.
Eventually Jerry stopped coming (due to time factors, or so he said.) Since them, my group bloated to 7 or 8 players and I formally closed the game.
Recently, a player told me Jerry asked about getting back into the game. When he told Jerry the game was closed because we had too many players, Jerry didn't see that as a problem; he simply said that his (supposedly CG) character would assassinate other characters in the party to make room. My player explained that it didn't quite work that way.
See, I see what you are saying about "live and let live." But at the same time, I can't help but feel that Jerry "got in with the wrong crowd," and if his formative gaming experiences were with a group that knew the game was about the group experience and not about glorifying his muncky character, we would have had a competant player on our hands.