Usually, with a perma-dead character there is some specific reason they are perma-dead. Sometimes it's elaborate, sometimes it's just a one-liner. "The poison doesn't allow for the use of resurrection magics." "She was under a curse." "There was, simply, not enough left of the body to bring him back." Etc.
On GL there was some EM fiction for Queen Dawn but I forget what it was.
Usually it just takes a one-liner to explain this; then on with the show.
Also some people RP UO game mechanics death as unconsciousness, and resurrection isn't resurrection per se, they "just" bring you out of a coma.
As to why anyone dies? Ever? We have to assume that resurrection magics are limited. The magical equivalent, perhaps, of a super-advanced CPR or a super-high-tech defibrillator. They can't overcome all forms of death, just much of it.
As to why people lose Fame when they die?
If you think about it, they don't.
You lose Fame when you res up. If you stay dead you get to keep your Fame.
Were I to RP this I would say that the NPCs like to reward victory; or like to reward heroic loss when the hero stays down.
I could also say that it's a form of Humility; the people acknowledge that even a great warrior can lose.
But, honestly, in however long it's been since I started playing this game, I hadn't thought about that.
As to Necromancy? Necromancy lets you manipulate death and the dead. Not rez, so not overcome death. Just use it to your advantage.
-Galen's player
