Personally, I'm in the fortunate position where $10 won't break me, but I'm not exactly thrilled with the increase, either. In the last few years, it's been mentioned more than once by individuals within the game industry that making games has become increasingly expensive over the years. Generally speaking, prices for the games themselves haven't changed much, or in some cases, gone down. Ignoring issues of inflation, you might have paid more for an NES cartridge in 1987 than you do for a big-title game today in 2014. It might be reasonable to expect a price increase, but Warlords of Draenor is among the first to make it so obvious.
Am I going to buy Warlords of Draenor? Yeah. Of course. WoW is what I do. But the price tag wants me to look at it like a brand new standalone game, not an expansion pack. Will I get more enjoyment out of Warlords of Draenor or some other big new release? Probably Warlords. A new WoW expansion is likely to last longer than, for example, Watch Dogs, even though I would enjoy both. Then again, Watch Dogs isn't asking me for a subscription fee.