Most of the people will use group search, in that case there wont be pr0 players with you on instance and while dealing dmg they will get agro for sure, and its not about if you are dmg dealer melee or ranged. MMO games going into way where players need to be more active than stand in one place and tank boss while there is heal and dmg dealer on side. This game shows that you wont stand in one place, you need to run around, deal some dmg, and whats very important dodge bosses aoe. So prepar for fights where boss got random target skill cast(aoe) and game where you need to be more dexterous than tanky(that will be only advantage).
I think healing that bunch of mess will be the hardest job( I will play healer).