EvilHoD: Severing -- better that than no foot at all. But, even so, the odds of something falling just that right way to bend the edge and not have the cap of the toe take the biggest part of the impact and roll off your toe has got to be extremely small. I've been around these things almost my whole life and never, ever heard of this happening. So, not saying it's impossible, just incredibly unlikely. And, as you say, if they are crappy boots than maybe the steel isn't bent properly to encourage the front or side roll, or the steel is crappy steel.
MuppetGirl: Ingrown toenails -- I would never ride with steel toed boots, only because my toes would get too cold, but how in blazes do you end up with your toes jammed up there so much and so often that you are pushing on your toenails? It may as well be that the boots are too small -- same effect. You'd have problems with most any boot at that. I have slightly deformed toes from wearing too small footwear as a child actually.
I will continue to wear my steel toed boots and runners when I'm working around things that go bump and things that cut. I guess I have the steel toed bug like others have the helmet bug! :)