Accuracy is on all my gear, but I haven't missed an attack since level 49.

I stopped missing attacks when I reached level 50. It seems the "hit cap" is so low that you're basically guaranteed to exceed it no matter your gear choices. However, accuracy is on nearly all tank gear whether you want it or not -- I have full Darklight and it's on literally all but two of the pieces. This basically wastes half of my gear's stats. What's the deal with that?

Accuracy is a vital stat for later raid bosses. Basically you need a certain amount of accuracy based on the level of the boss you're fighting. The problem you're seeing is that you get an accuracy bonus for being in a 4/8 man group... and that accuracy bonus is enough on the FIRST bosses (and 4mans) to cap you.

For now it's wasted, later on you'll be wanting to stack it.