1. Having a game where there is a "high likelihood" of PCs dying, multiple times, in a low-level game. No, thank you, I do not want to roll up my fifth new character for this campaign. And you wonder why people have stopped giving you backstories to work with...

2. Ex post facto fixes. I understand most people do not like the way diplomacy works as written. But if you wait to fix it until the first time my character with a maxed-out diplomacy score tries to use his defining ability, I will not be happy.

2b. Along the same lines: forcing a roleplaying of a diplomacy or bluff check. I appreciate the possibility for a bonus due to a well-phrased request, but do not force me to try to phrase the request appropriately. We are role-playing. You don't force the fighter to actually jump up and down every time he makes a Jump check "for realism's sake," so don't force me to actually try to bluff or negotiate. The reason I'm role-playing a character like this is because I'm terrible at it IRL, and I want to fulfill a fantasy of being a smoothtalking person.