Said this in other forums, I'll say it here.
These nerfs came because Q3 ends next week, and come November, Blizzard's financial people are going to have to publicly explain to their investors that World of Warcraft has lost subscriptions three quarters in a row.
In Q1, they reported dropping from 12M to 11.4M, and Q2 dropped further to 11.1M. That's a 9.25% decrease in their subscriber base over 2 quarters.
If you want to know why they did something so drastic -- there you go.
It's not just that, but also a way to get 4.3 out sooner so that it conflicts with other titles rather than Diablo 3.