Grouping...Its an MMO right?
I group because I want to play together with other people. When I'm picking up my herbs for my alchemy, its nice to know theres a stealthy out there who has my back just in case some bandits are getting some nasty ideas. I want to be able to step in and absorb a blow for my cleric who's been looking out for everyone but himself. Don't forget laying on hands on the warrior just so she can get a critical hit on that god ugly gnoll that got the better of our mage. I can't wait to stand there bashing and stunning up some over built construct so the assasin in group can polish it off. I would think nothing of laying down some crowd control so my party can escape even it means I'm gonna go down. Those are the magic moments; the ones you take back to the tavern with you and recount over flagon of ale. Then theres just the friendship you develop just because you let someone get first pick on the loot, or lent them some bait so they can get that big one. Especially if its the one you couldnt get.
I grouped up in the last beta plenty. I had one pairing with a guy who had never played an mmo before. It was fun going through the newbie steps and wonder...for me. Thats just me. I also had a pairing with a DK who was going light armour but wanted to try the heavy just for giggles. We stopped at a crafting station (Orc side) and I banged him out a full suit. I even threw in a couple of enchanted weapons. The guy was so happy youd think he'd won the lottery.
And that's just the elves and swords version. I played City of Heroes from beta to close. OMG they had aireal combat. I will never forget flying over Paragon City and peeling off in our formation to get the drop on a pack of sky raiders. 360 camera views were amazing and immersion was just crazy. One of the few times in all my years gaming I was screaming for my wife to come see! I still get chills just thinking about it!
And this game has that synergy thing going... thats just awesome.
A million reasons to group. Those are just a few off the cuff. Yea, there's a lot of bad out there, but that's life.
Just look for the good and the good will follow you.