The addition of automatic gear drops for the leveling dungeons was a really wonderful change, and while that wouldn't necessarily be possible for the Capstone dungeons, I do think that having coffers for it would be a nice compromise!

Capstone dungeons (IE. Lvl 50/60/70/80) are kind of a bugger to run over and over trying to get certain gear to drop. Adding some coffers in the boss chests would probably make them a lot more friendly without stunting the queue too badly.