I'm all for allowing companions to be killed, but in regular combat it was just an annoyance. "Oh, he died, let me just reload that save," or "great, now I got to go to the temple and resurrect him." I could try and force myself to leave them dead, but if I liked them and wanted them around, it just wasn't worth it. And resurrecting them really cheapened death.
If I want to kill my companions I should get the option to fight them to the death, but other than that, narrative deaths have more meaning than random combat casualty.