I'd say it was the norm. Never met a guy who wouldn't go down on me, or who didn't expect the favour to be returned.
Obviously enthusiam for giving, and receiving, oral depends on the person. Some people love it so much that not having it or not being able to give it would be a deal-breaker. For others, it isn't important.
My current boyfriend rarely gives me oral, he likes it but I rarely ask and have told him receiving is nice but doesn't really do it for me often in a big way. He also seems less keen on receiving than my ex. But even my ex, for whom receiving oral was the pinnacle of all things sexual, had been out with women who wouldn't give it. He didn't push the issue, but I think he really missed it from what he's said.
I see oral both ways as pretty essential, at least occasionally, but then that's me.