The best thing blizz can do is drastically scale back monster power health and boost monster damage. Then people will gear more "balanced" and less "glassy" right now 95% of people are seriously obsessed with dps and overpay for it.
They'd have to scale back player damage, if they're scaling back monster health; right now, the highest DPS players in the game can already kill monsters so quickly that incoming damage is moot.
They'd also need to restore players' defensive skills, if they're going to restore monster damage; they nerfed damage because they were nerfing defensive skills, in order to encourage players to build more offensively.
The thing is that the initial (and imho biggest) mistake that made everything go to hell was overscaling healthpools. In it's original iteration, the MP system was somewhat manageable, because ranges weren't so big. MP10 went up to 400% hp, which was fine. Then they decided to not only nerf it's damage, but also overdo this health scaling reaching up to a completely absurd and unmanageable 3500%, like it added any difficulty at all. All it is is a lame dps check.
If you notice, that's the only reason why certain skills have been overbuffed, and why gear got "doubled", leading to an unmanageable amount of dps, making any sort of balancing pretty difficult. The existing layout didn't support this obscene overscaling, so they've been stuck trying to rebalance everhyting ever since. However, most skills remain untouched, which only made them even more useless next to those overbuffed ones, severely limiting build diversity. All they've been doing is providing FOTM builds every time they overbuff something. For instance, look at Rapid fire for Demon Hunters. The skill is so damn overpowered right now that more than half of the demon hunters out there rely on it. Same goes for many other dominant builds, which feature at least one of these overbuffed skills, such as wave of light, cloud of bats, or hammer of the ancients.
This is a problem itemization won't fix.