Yeah I just had a great time with my UCSD friends....if we weren't out near SDSU, in Mira Mesa, or in gaslamp....we would just kick back on campus (when they were in the dorms/on campus apt's).
So yes, UCSD and other suburban campuses lack the "feel" that many older schools back east (or even berkeley) have (ie greek rows, established campus zones etc...), it doesn't necessarily equate to a lack of community. That'll depend on who you associate with and what you all want to do. My UCSD pharm friends party like nuts...my facebook feed is filled with Vegas pictures and gaslamp stories from them, and when i'm in town we'd have BBQ's. At the same time, I know dozens who just hole themselves up all day and night.