3.20 Obliterated Bane's damage -- why?

Summary:

3.20 lowered the damage of an optimized Bane build by 40% against most enemies, 20% against rares, and barely increased it against uber bosses (which was always what it was worst at anyway). Bane was already a sub par build, and now it's even worse. Why!? Why do you nerf builds that are already not very good!?

Details:

Let's consider an extremely optimized (hundreds of divs) Bane build. In 3.19, you could get around:

- 150,000 tooltip DPS from Bane plus 330,000 tooltip DPS from Essence Drain
- 100% increased curse effect
- Level 30 curses

If you're applying Despair, Enfeeble, and Temporal Chains, this resulted in about 1.2 million DPS from Bane against a rare with 0% chaos resist, or 3.5 million dps with a decent Essence Drain on as well. A lot of this came from Despair's additional DOT damage, which was completely removed in 3.20.

If you used Punishment instead of either Enfeeble or Chains, this did about 1.9 million DPS from Bane, or 5.5 million including Essence Drain.

In 3.20, Despair was nerfed, Punishment was nerfed, and Bane was nerfed! The same build now has 50% increased curse effect. Curse effect is easier to get on the tree now, but harder on items, which feels like a wash, but let's be generous and use our legacy items and say we have 65% increased curse effect (an extra +20% from the tree).

Without Punishment, the same build now does about 770k DPS from bane, or 2.2 million DPS. This is 63% as much damage.

With Punishment (I had to guess on the new level 30 value because I'm not gemmed for it right now; I guessed 70%) the same build does 1.16 million DPS from Bane, or 3.3 million DPS including Essence drain. This is 61% as much damage.

Why!? Were chaos DoT builds really broken before? Bane was never an uber build, and it had already been nerfed when it lost the Curse tag. Now it's even worse. It's a fun build. It's my favorite build. But you can't stop making bad builds even worse, and I don't understand why!