Suzie - yes I agree there, but I do think that language is not all logical. For example the phrase "by and large" or the statement "It's early days yet" are both widely accepted correct idioms - and not just regionalisms or slang, and yet when you try to analyse them they don't make sense.
I tend to draw a parallel with music. There are rules of harmony and the default position is to obey them, but the tutored ear is the final judge.
I certainly wouldn't interpret this as an "anything goes" attitude. I do think knowledge of the rules is important, even if you end up breaking them on occasion.
I quite like "Fowler's Modern English Usage" on this issue. His discussion of the split infinitive is particularly good I think.