TBH, the news to me is that some people _don't_ get hypnagogia all the time. Or I guess they wouldn't start associating all sorts of meaningful meanings and supernatural explanations to them.
For me it happens almost every time I go to sleep. Though I can't remember it ever happening while waking up.
It's usually nothing particularly meaningful or choreographed, though. Mostly patterns, images, often morphing from one image to another, a drive-by view of some simple landscape, things like that. Though occasionally the image can be something deeply disturbing. They're rather faint though, nothing particularly vivid.
In the meantime I can even somewhat control it. If it starts taking a nasty turn, I just start thinking of some lovely landscape or whatnot, and the brain usually obliges with the visuals for it. Occasionally it may take more than one try though.
I wonder if that makes me crazy or something

(No, really, now I'm curious. If you're a doctor, please do comment.)
At any rate, it's quite difficult for me to take them as some meaningful message from beyond, or view into spirit world or other dimensions, when I know essentially I can get any other image _I_ wish there. If I can morph hell into a lush tropical scenery, or some ancestral ghost into, say, my last Dragon Age character or into a tropical island or a house -- and then it occasionally falls back to doing its own thing and morphs into something different from both -- it's quite hard to start imagining that I've actually seen hell or that an actual ancestor was trying to give me messages from beyond. It's just images that my brain seems to like to play with, and there's no major difference between the ones happening spontaneously and the ones I can basically order myself.