It's a buyers market and the choice out there is so huge I would never buy a damaged guitar purely because I don't have to, nothing more, nothing less than that.
I saw a sweet Melody Maker for £300 a couple of weeks ago, perfect condition. When that kind of deal is out there there's really no need to buy a damaged guitar, imo.
Guitars with broken headstocks are good deals if you buy them at the right price and for yourself to keep.
Because they play just as fine as guitars with unbroken headstocks.
The problem is finding a buyer for a guitar with a broken headstock if you want to get rid of it...
I have a few with headstock breaks, and apart from their severely diminished market value there is absolutely nothing wrong with them