That's not so bad if you're a Protection Warrior gearing up for heroics or Karazhan, but if you're spec'ed to try and do damage, you're going to be fending off a lot of invites. Your next step is to explain that Warriors can also do dps (or can they?) and try to get an invite yourself. In my experience, Warriors aren't very beneficial to have along. They provide few support roles, at most an attack power or an hp buff to their group, if they are coordinated they can offtank but that's just about it. They are very gear dependent and tend to put out a lot of threat with careless use of Whirlwind and Cleave. I'll take an Elemental Shaman, Hunter, Warlock, Mage or even a Retribution Paladin before inviting some random Fury or Arms Warrior.