Artsy people can use capacitive styluses (styli?), too. From what I've read, the Wacom Bamboo works quite well for this. The suggestion by Dick Applebaum is a possibility, too, although it's 3X more expensive.
I don't see why iOS wouldn't *support* a stylus. If you're one of the few people who would benefit from one, you're welcome to find one on your own, it's just that Apple has decided most people won't care, so they don't sell one as a default.