Its not that I wouldn't have minded it, but....wouldn't the Emperor ya know, see a blade being thrown right at him or sense it and avoid? Am pretty sure he isn't stupid or blind, unless he was focusing all his attention on Revan...though there is a slight difference between the two deaths. Vader just went up to Palpatine, and picked him up...wouldn't throwing a lightsaber take time to actually hit the person? Now this is where, I see the flaw being the Emperor would have a small window to dodge or w/e.
Thats just it, he cant sense Meetra or her attack, she's a wound in the force.