My understanding is that all iPhones will have handwriting recognition for Chinese (and Japanese, too? Eh, I'm too lazy to look up the answer) regardless of where it's sold. Good for the bilingual folk...
The reason why you don't see it for all the languages iPhone support is that it's a really difficult technology to get right, made even more so by differences in languages. (Try to use Inkwell on your Mac and you'll see for yourself.) Plus, with most Western languages, an alphabet means a virtual keyboard is much more time-effective than drawing individual letters on a screen with your finger without any obvious method for separating a string of inputted letters into words and sentences.