I love hit and expertise. While their mechanics and nuances can be complicated, I enjoy the diversity they bring to our gear options. We have stats like critical strike chance, which give us a chance to hit harder; haste, which lets us hit more often; and of course, hit and expertise, which let us hit our targets more often. The interaction between all of these different gear stats is one of the most interesting parts of theorycrafting for me. Think about it, would you really enjoy picking gear if you were just choosing between haste, mastery, and crit?
Unfortunately for us, hit and expertise are also our only two remaining stats with tangible caps on their potency. While we were able to cap out on critical strike chance and armor penetration in the past, one of those stats has been rebalanced and the other completely removed. Because of the caps in place, hit and expertise's value drops off immediately after reaching that golden value, and so we're left always keeping those caps in mind.