I was wondering why more websites weren't already doing this when SOPA/PIPA were on the horizon.

The US has a problem with politics and when that problem endangers the internet, to me at least, the simplest solution is to block US users.

It has got to be tempting now for site owners, especially considering how US courts do not seem to have much trouble seizing websites. If the site isn't US facing surely that would put a big dent in any legal action made stateside.