The questions asked assume a number of things which are hardly established facts, namely: 1) that the female character design in Blizzard games is 'hyper-sexualized' in the first place; 2) that Blizzard's character design won't empower some people and they won't feel "awesome"; and 3) that Blizzard doesn't care about empowerment.
It'd be like asking President Obama something absurd like "Why are you hiding the fact that you weren't born in the United States?" when there is no evidence (and quite a lot to the contrary) that that's the case.
There's hardly a theme of hyper-sexualization in Blizzard's games if you look at what they've produced as a whole, unless you happen to think this is somehow hyper-sexualized: