I've seen several such doors- indeed, I had to look closely to see if it was one I recognised!
Such doors are rather common- and usually enter a maintenance or boiler room. I will concede that they usually don't look quite so nice- and the addition of a step or two wouldn't bother me at all!
Another situation where head clearance can be an issue is when the door opens immediately to a set of stairs.
I don't know if there even is a proper solution....signs have to take up a certain amount of space (especially if there are 'bug eyes' as well), and you can't really ,mount them ON the door......
Wait....aren't there approved glow-in-the dark exit signs these days? One of those could be posted on the door.
I still see a need for a more compace sign, though. Maybe someone will make one.