That's also been looked at, and while it's a much more viable option than captains kicking at will, there's always the risk of people trolling, or experienced players kicking newcomers just so that they can get somebody else on. This would have a largely negative effect on the community (especially new players), and that negative side may very well outweigh the positive side.
And if you really have a nasty troll on your crew, don't worry. Those guys don't usually spend much time on the same ship anyways. And if you find a newcomer who's doing a really bad job, you can try explaining the game to them. If that doesn't work, you can always look for another ship.