well heroic shields were originally implemented to extend duration of the boss fight so that you actually had to learn and survive the mechanics of the boss. To that end, I think the removal of the heroic shield and increase in boss life is a better means of accomplishing that end. Some of the fight mechanics should probably be reworked though.
The changes to kab have made him laughably easy. True, the bone prisons cause a great deal of desync and frustration and I'm glad they're gone, but something should be changed to make it more challenging. At the moment he can be realistically done as soon as you reach act 3 destruction by any build that would be capable of killing baal at that point.
Quov Tsin is fine I think, reasonable life, trinity beam requires resistances and dr so it's still the same kind of gear check it always was, just less intensive (maybe bring back res pierce to increase gear reqs, since it's quite simple to get 90 all). Bone nova skill requires you to pay attention since it's a 1-hit ko but it's not hard to avoid, so feels fair.
Astrogha is a bit tougher than it used to be. I don't think there's anything really wrong with this uber, except that if you let too many darklings pile up, it takes a few seconds after entering tp for the area to load, and if you're close to the swarm you'll die before you have a chance to do anything. Solution to this is to just make your tp further away or outside the entrace. The first time I attempted it I let so many darklings pile up that after I left the game I was unable to rejoin it, similar to how it could get when doing old cancer-uldy.
I like the changes to Xazax very much. It's a timered fight based on not letting the area fill up with invincible darkwardens

Straight damage check where you need to mitigate adds that get in your way/kill you fast if you let them get close/block the boss entirely if you let too many get summoned. No more cancerous chasing him around hallways

Belial is pretty much the same, not much to say here.