I'm not sure that it would be socially responsible to show a dementia patient being so dangerous though, there's already enough stigma about the condition.
Also, the flashbacks with young Kes were the only part of the episode I did like! Still, even that would've been a lot better than what we got.
I'd have rather not have had Kes return at all than the character assasination story we got. At least they were talked out of killing her off.