Just to add a minor point, the tricky part is this: the person that got kicked, do we issue him an penalty (of some sort) or not. If we do, then how do we deal with the case of "unjust kicks", if we do not, then the vote kick feature will get abused into a "game disband" feature...
The worst case scenario I've seen is premades using it as a way to bully the randoms into doing what they say.
My suggestion is to outright disable the function for any premades to vote-kick. Let players KNOW if they have premades in their team. This is a feature for solo queue randoms, so premade teams of 5 won't need it.
If you have a team of 5's, and there's a duo queue. Only the 3 randoms can choose to vote kick a player, requiring a 2/3 majority to succeed. And if one of the duo queue can be kicked, the partner will be kicked automatically to prevent any angry counter-attacks.
The hole so far is 4-man premades with 1 random...
There could be some abusive situations, like forcing the meta. But it's a far more attractive alternative to losing 34 ELO because some idiot who won't speak up till the end and refuses to Support when asked what he wanted at the beginning ending with a duo top game because no one was willing to support bot resulting in a situation where Draven is suddenly forced to solo a Kog+Taric lane and result in a super-fed Kog carrying the enemy team and getting an easy free win over us while the duo top are under-fed and levelled because they focused so hard on competing over CS. *rage*
In short, the pros far outweighs the cons I have to put up with.
No offense to RIOT, but its true that its gotten to the point, where League of Legends is slowly becoming NO fun anymore and just a pain in the rear-end.