It does do it, actually. Corpses have a chance proportional to burnt/volume to become unrevivable except by necros. This is rolled at revive time so it isn’t displayed until that (will still be yellow in UI), but a badly burnt corpse shouldn’t rise.
Also, I recently buffed fire vs. (item) flesh effects, so corpses should be easier to burn. Still not as fast as butchering them though - this will need a separate fix.