I thought I remember reading somewhere that SE didn't want to give DF groups kick power for some reason, but I think they totally should have an option to kick idlers... maybe have the game notice if they've idled for 5-10 mins and then make the option available? You wouldn't normally be standing still in a dungeon for 5 mins anyway, so that would be a good short amount of time to use to determine that someone's AFKing.

As a main tank for CM runs, I despise AFKers, and I think the problem is a lot of people have this attitude like "well, f*ck it, let's just get on with this so I can get my stones." No. If someone's clearly AFKing, I will stop tanking and demand that person join the group. There's no way in hell that I will ever allow that behavior to pass unscathed. If they try to call my bluff and stay AFK then I will simply leave, whether I end up taking the 15 min hit or not. If I do, then I just craft or fate grind another class for that time period, no big deal.