Originally Posted by Frost
It's because misspelling words is cool yo, rebellious puberty induced angst at its best.
And in the teenagers quest to make worlds as short as possible to for the purpose of sending instant messages, the world "new" was determined to be just too long of a word at three letters.
Although, in a way, it's helps identify the genre.
New Wave is still called "new" even though it's hey day was 25 years ago. But no one wants to call it "Old Wave". The term "New Wave" is simply a misnomer at this point.
Nu-Metal won't have that problem, as Nu will still be a screwed up word identifying the genre properly, be it 10 or 50 years from now.