Same here, even solo'd 95% of my time in mmo's. As I recall all B1 story line was all solo-able There may have been a side quest for a raid boss at the end I do remember grouping up for a dlc boss at the end. Also by skipping 'release' and playing the games a year later I generally find you can miss the worst part of pug fags in the beginning. Also I had pirated all games up till last year and we were using a program (Tunggle) for borderlands that allowed internet gameplay for pirated games that had LAN enabled. So it goes without saying it wasn't your typical online console culture.
(20 days old, so may not ever read)
I did buy borderlands packages when the were on sale awhile ago OP, (haven't replayed much more than act1 of B1 so far) so if you want to give game a try, Im willing to play a bit.