Waller: make walls destructible. It is not fun to be locked in the sewers, to be unable to play, to die (also in HC..) because of them. It would be a funnier gameplay mechanic to actually have to decide quickly to either evade the tough situation, or to shoot 2-3 times to destroy the wall. Giving the right amount of HP to the walls is actually the key here.
Same is applicable to:
Arcane Enchanted: as the arcane trait grows, it should be destructible as well, if the player is not fast enough, the trait is there to stay.
Frozen: same again, destroy it, avoid it, or take the damage.
Shielding: well.. need I say it ?
For the new affixes, I would like to see more affixes like Health Link, which I consider as a positive affix with a trade-off. Positive because we can isolate an elite and hurt him real bad before we take care of the rest, the trade-off being that we sacrifice a player to kite the rest of the group.
Give us buffs with constraints.