Remember that uncouth still lets you buy social skills (albeit at double cost), while for incompetent, you have to buy off the flaw itself if you ever want to get the skill. Also, taking separate incompetencies will increase your Notoriety more than the single flaw of uncouth will.
Unfortunately, Shadowrun's social skill rules fall flat on their face in some areas. Since social skills are resisted with social skills, you can't really make a decent curmudgeon unless you also make him a face (which is defeating the point!). If you have, say, incompetence in etiquette, then part of it plays okay - you are likely to wipe your nose with the tablecloth when you are trying to fit in. But unfortunately, you are about the opposite of antisocial when people use etiquette on you. You want to be everyone's friend! Because you don't even get a roll to resist it. Bah.
I think being "unaware" in a social skill should confer near-immunity, not total vulnerability. How can you succumb, when you are standing there going "Derrrrr..." while this person is threatening you, trying to seduce you, or whatever else?