WoW had it. The leader of a raid could initiate a ready check. This would cause a box to appear on everyone in the party's screen that would say click OK if you are ready. After a few seconds, it would return to the leader the number of people who readied up, or if everyone readied up, it would immediately say everyone is ready.

At the very least, they should make it so only the party leader can ask to enter instances, and when they do, prompt the rest of the party to click a button to be ready in order for the team to enter.