Frostbite and hypothermia are two different things and often happen under different conditions. As noted, you can get hypothermia in (relatively) mild temperatures if you're wet, tired, dehydrated, etc. Frostbite tends to be the result of colder temperatures often in conjunction with wind. But, yes, both are bad. I've also had fairly mild frostbite of the ear lobes (a pretty common place) and it's not fun. The thing to be aware of though is that it doesn't have to be especially cold to get hypothermic. In cold weather hiking, some of the conditions you need to be most careful in are 35 degree or so rain.

I've been lucky enough to never experience real hypothermia first hand.

Mild frostbite != blackened skin. I'm curious of what situation you got yourself into because that sounded fairly serious.

My pants got stolen while I was attending life guard classes. I had to walk home in ~30 degree weather in the snow in wet swim trunks.

I sometimes make bad decisions.