Joanna, Cal alum
Most freshmen seek off-campus housing in their second year, including me. It was almost like a rite of passage--you weren't really advancing unless you found an apartment or house with friends in your sophomore year. In fact whenever I encountered senior classpeople or grad students in the dorms, I always wondered why they decided to live amongst a bunch of rowdy 18 year olds. Later we would make fun of Stanford graduates for not knowing the first thing about negotiating with a landlord about fixing a leak or getting through to a bored/disdainful school admin to get what you need.
Living off campus meant you were plopped into real neighborhoods, with real people (and real dangers), but you were doing it with friends, so it never felt isolating or scary. Plus campus was big enough that it had its own gravitational pull so you never felt completely alone. Weather was never a factor (like being snowed in). The city didn't swallow up the university (perhaps like NYU), nor did the university dominate the city. Oakland, the neighboring town to Berkeley, was once called the greatest little big city in the U.S. by a reporter friend of mine.
P.S. this is all southside living, don't know how northside dwellers fared! My impression was that it appealed to quieter living.