I picked the one requiring things to be expanded on. First off, I actually know people who met on MMORPGs, so evidently they were nice to each other. Also, I've developed some friendships on MUDs, so unless 3D graphics drastically change the experience, I think you'd be a bit off.
The difference though with MUDs is that people weren't spending money, so the whole experience was much more casual. No grind or trying to play your classes right, I remember building a character purely with charisma that had no benefit otherwise, but I was trying to get every item that gave a charisma boost. People thought it was cool. I figure the deal should be the same with Guild Wars 2 - no money being spent, so no major investment, no specific types of classes so you can solo as well as work in a team. In that sense it's much better, you can play the whole game by yourself if you want, so if you end up working with people it's because you like them not because you have to to fill your party out.