99.9% of former and current WoW players, who play DDO, are not the problem. This note is not intended for you.
For the minority who is:
Some of us like to focus on the adventure at hand, and could care less about your level 80 Paladin or Bear Shaman (or whatever). Please stop talking about WoW because we aren't playing WoW. Believe it or not, there are people who actually exist, that have never ever played WoW. Some have tried it, and thought it was bunk. When you are talking about it, it's like playing with people that have a conversation in Russian or Chinese on voice, only you can understand parts of it.
There are some of us that would rather stick a fork in our eye than stay in a group that won't stop talking about another game instead of paying attention. I don't need to go into detail about what happens in a difficult dungeon when people don't pay attention. Some quests are difficult enough when we have everyone's full attention.
That is all.