Okay, you know what, I'll make it very, very simple to you:
I'm sorry, it's very hard to hear you over the condescension...
Imagine DC decided that their official Superman didn't come from another planet, after all. Imagine DC telling us that Batman's parents did not die at all. Now, if you can imagine the outrage over that, add to it a gender-political level, and you may begin to understand.
*sigh*
I'm not an idiot. I understand your... "outrage," I don't AGREE with it.
Though, to address your points...
If Superman wasn't from Krypton, I don't think I would be all that outraged. (Actually, to be honest, I don't know if there is anything that would get me outraged. They're just comics.
I would argue, like Diana, Superman being from Krypton doesn't really motivate him. It does provide him a reason why he has powers, but, it doesn't motivate him. His Earth parents are the ones the instilled him with his moral code and ethics. Other than an otherness--which really doesn't get address in the comics often, his origins, like Diana, aren't that important to the character.
Bruce's origins on the other hand, the death of his parents, motivate his actions to dress up like a Bat. But, then, the Batman of Earth 2, Thomas Wayne, took up the mantel after his son died. So, perhaps there are other ways to motivate it.
Perhaps if you had said, would I be outraged if instead of a lightning bolt striking Barry Allen giving him the powers of the Flash, that he, I don't know.... inhaled fumes from... I don't know... hard water and that some how got him the powers of the Flash.
Oh, then I would be outraged.