I am going to agree with the (sane) logic people are posting here. This is an MMO, and there should be more incentive to bring along full groups of people and be social other than "it's just faster!". Why not have that bonus of having a full group that EQ1 had as long as the coding allows for it?
I too am one of the people who cringe on the inside when more folks want to join in on an XP grind group. I'm not going to turn people away if they ask, but I'm not likely to offer because I know I'll take such a huge XP hit. I should be wanting to bring more folks along here!