I'm a year-round bike commuter, and I really appreciate those disc brakes when I'm biking in heavier rain. Don't underestimate how much better they work than rim brakes in adverse weather conditions.

I'd say it's just the other way around; disc brakes are most useful for commuters, and least useful for dedicated race bikes, because you just don't go out racing when it's raining a lot (and you're typically on a closed course besides so there's less braking).