1. It usually comes installed on great hardware.
2. It's less vulnerable to most things than Windows.
Beyond that, if you choose to build a Hackintosh, in my opinion you (for whatever reason) enjoy OS X enough to depend on it but don't like Apple enough to run their OS without paying their hardware premium (entirely understandable from the price perspective but a little illogical if you take it a bit further).
Frankly, I can't see any reason for the Hackintosh middle ground other than people who can't cope without the OS but can't afford the hardware. The software is little more than a neutered and compromised version of BSD that lets you part way into a walled garden (cue It's a trap! meme).
Granted: There's also the requirement of a Mac for iOS development... but guess what? You're still stuck with the developer program membership fee. Save $500 here, lose $100 a year there, along with probably being in violation of half a dozen usage limitations.