I thought that about Tasha Yar in Skin of Evil.
Yeah, I saw that episode, too.
Huh?
After Skin of Evil, there wasn't a single moment in the entire series when I thought that any of the main cast were ever in any peril.
Maybe you can look over http://en.memory-alpha.org/wiki/Skin_of_Evil_(episode)#Reception, and tell me why the producers would have pulled a stunt like that again. Start with:
Most involved with The Next Generation felt that "Skin of Evil" was an unmitigated disaster