I prefer to ride alone for various reasons:
1) Attracts less cops.
2) I stop when I want to stop (often ride 2-3 hours without stopping...need gas), not when some 'tard feels the need to stop for a smoke, dip, drink, piss, etc every 10 miles. Hate that shit.
3) When I go sport touring, I go RIDING. If I wanted to hang out with a bunch of guys and talk about bikes I'd go to a shop.
4) I ride at the pace I want (slow, medium, fast, supersonic), when I want, anytime I want. No need to worry about slow people keeping up or keeping fast slowed.
5) I take the routes I want, when I want, with no discussion.
6) Get tired of people asking me what I'm listening to on my MP3 player.
7) Peaceful bliss to get away from everyone.
But this is just me. Some people dig big group "rides" where you spend more time stopped and talking than actually riding. Not me.