I am half American, and whenever I speak to my family across the pond I find myself reverting to my father's accent. I also find myself using words that I wouldn't normally use in my day to life. I mention this because a lot of the pet hates featured on this thread are colloquialisms, which are of course innocent phrases people revert to when they feel comfortable and amongst their own. I think it is wonderful that language is such a pliable form of communication with new words and expressions constantly seeping in. I mean, where would we be without jargon and slang? If I had said "I wanna bonk that chav" aloud in 1943 nobody would have known what I meant, whereas you lot immediately understand what I'm saying. On the other hand, chances are that a lot us would not fully understand some of the phrases used by people back in 1943. Language is alive and living, a constantly evolving entity, and that is exactly how it should be. I'll probably be shouted down for this, but I do think dropping haitches is the modern day equivalent of spreading brand new language seeds.
I also think it is rather unfair to expect that language, grammar and spelling should mean the same to everyone. I am a scientist by profession and nature, and to be absolutely honest English bored the pants off me at school. How I wished those utterly boring lessons away! I make atrocious grammar and spelling mistakes on a daily basis, yet I don't lose any sleep over it. If, however, I make mistakes with issues to do with treponema pallidum haemagglutination or adenosine diphosphate it will bother me for weeks, months, even years. This doesn't mean I don't care about our language and its use - I actually DO think it is important, but not overly, TERRIBLY so. The ones who really do care about the finer points will duly become our beautiful speakers and magnificent writers. We desperately need those, so that's great. The ones that don't care all that much will still be understood. The ultimate aim when using words is communication, and this is something most people do master.