There is a difference between manners and formality. Manners are important in that, as people say, they're civilized and they just make everyday life more pleasant. Formality - for want of a better word - however is extremely annoying (e.g. 'you must respect your elders.' irritates me no end. I'm polite to my elders - but I'm not just giving my respect to anyone unless they've earned it. If you have to order people to respect you, then in my opinion you don't deserve it.)
On the learning of manners, I'm not sure I agree on the parental argument. Sure, parents are important in that they should support what you learn, but in my case it was really my school which taught you basic manners. To give one example, I'll instinctively hold doors etc. without thinking of it simply because it was drummed into you at my school. But then, I guess, this is just my experience.
I have to say, though, bad language really doesn't bother me. I do accept that there's a time & place where it broadly isn't appropriate though (restaurants etc.)