Well, I have seen the option in two games, and it seems to work great. You can try the games for yourself and see how they work.
Game number 1: TrackMania Nations Forever / United Forever. They have millions of players, and they use a majority vote kick/ban system, and the game is played by the non "mature" as you stated, and it does work and is not abused.
Game number 2: Runescape. Runescape has a huge reporting system. I don't know how many reports a person has to receive to get banned, but I have played the game a lot, and people don't get banned for no reason. Also, if someone was banned for no reason, they can protest to get unbanned.
So two out of two games I've seen use this sort of thing, it does actually work and is not abused. At least not to the point of make it a pointless feature.
Also, I just thought of a another feature to make it work better. Only allow each player to report someone 5 times a week, or month. That number would have to be discussed. But anyway, that would make the player be more cautious about doing their reports, and only report those who should be reported.