+1 to the idea of disabling attack speed attribute.
However, -1 to the idea of disabling PvP in the End.
I don't think disabling pvp in the End would help. I personally think that the end is a place where people can have fun and compete with each other, along with taking down the ender dragon. Disabling PvP would make it a lot more boring. If you wanted to work with other people in taking down the dragon, you'd probably have a talk with them and agree to work together.
It wouldn't really be necessary to encourage further teamwork. I don't see how that's very important. Perhaps a sign suggesting that you should work with your friends? That seems a lot better than disabling PvP entirely in the end.
Hey, maybe if people you find a group of people you'd like to team up with, YOU can become the "OP guy".
Great suggestion though. ;)