Like it says at the end of the article, why would I want to take something awesome (like a vibrator) and teach myself to associate it with the unpleasant hassle that is waking up? I'd never be able to fully enjoy a buzzy toy again! Just hearing an alarm clock go of on some television show is enough to set every nerve I own on edge, for Pete's sake!
Besides, I move around a lot in my sleep, and it would probably not stay put. Plus it sounds just plain uncomfortable.