Server admins can set the messages to display less often. We have ours set at 45 seconds between messages. It is far from disruptive.
As to the other suggestions, the problem for a server admin is that if we do not scroll our server rules (for instance), then I (as an admin) spend all the time I should be enjoying the game explaining our specific rules over and over again. When they scroll by then guys will see them and that makes an admin's job far easier.
Originally I had wanted to put them on the MOTD page --- however we are limited to just a very few lines there with limited characters, so that doesn't work.
In closing, if you are a community/clan that desires a more tactical style of play in your server (as we do), then the scrolling messages are extremely helpful. And seeing a message every 45 seconds is not horrible disruptive. I will say that once mod tools are released and mods are a reality, then many of our 5-6 "rules" will come down because the mod will make the violation of many of these specific rules impractical and or useless to the player.
I hope that makes sense.
