In the trailer, they actually reference the original Karate Kid, some of the bullies mockingly saying to Jaden Smith's character "What are you, the Karate Kid?" So it's more of an homage than a remake is kind of what I'm getting. I've also heard surprisingly good things about it.

So you're right when you say they'd be better of making a "similar movie" and that they shouldn't be selling it as a strict remake.

For some reason, I find myself in a minority of people advocating this movie. Then again, I could be wrong.