there can be (and there are) young players reading messages. We received messages from parents not happy about the possibilities that their children could read them.

There are many communities around the world and everyone can feel the same message more or less offending. There is no a fixed level for this, so we have to use as a parameter the lowest one.

Among our users there will be surely people thinking very different on many arguments. The only reason keeping those users here together is the possibility to play.

Probably those users have no desire to confront their opinion on these matters with someone with diametrically opposing ideas, but if you give them the possibility to do it, a flame war will surely start.
We are only trying to avoid it.

The original reason was technical. Currently we have have great difficulties on killing a single message in the forum. If there are several mesages to kill from a thread, it is much simply killing the entire thread.
This is going to change with the next forum release.

Anyway there is the possibility that after deleting a message someone will repost it. Killing the thread fix the problem once for all.

This will be done in the end, but only if we will be able to find someone willing to moderate it. As I already said, there are laws around the world stating that we could be declared responsible for what someone write in our forum, and this could be a big problem. We have to find a way to protect us from this kind of problems.