Makes sense if you're a shop, not sure why you'd send out just a single pipe to be powdercoated when high-temp paint works so well.
High-temp paint is cheap, generally flat-black, and cures itself the first time you run the bike. For these same three reasons, it's easy to touch up when you inevitably scratch that lowest-hanging-part-of-your-bike against something.
Do you want a color other than black? Is that why?
I would jump at the chance to economically powdercoat _any_ other moped part.