And of course the 'less' and 'fewer' thing. Really winds me up. Part of my job is proofreading so I'm fairly aware of these common language/grammar mistakes but I do dislike them.
As someone above has said, language does change and move over time, and it certainly has a great deal since Shakespeare. However, I think that now we have almost universal literacy and huge numbers of printed books, that might mean it's more suitable to fix the rules as they have been used zillions of times in ways to which we have access. I can't see we'd ever manage to do the equivalent of the German Rechtschreibung (spelling reform) they did in the 1990s, and they're still struggling with it. There will be new words generated (iPod, Internet) but I feel very resistant to things such as 'medalling' (as a verb) and to dumbing down.
But then I'm clearly an old fart and it's part of my job to like the language status quo.
(By the way, in Germany younger people often don't use the genitive case now, they just use the dative instead, so it's happening there as well...)