To her, mentioning a lack of racial diversity is just an honest critique and is meant as nothing more, to plenty of others she's saying the show is racist and we should react accordingly. It is the internet.
I honestly can't say how I'd react if suddenly the show I'd been working so hard on for years was suddenly being criticized for something like that. So, yeah, could the writer have handled it better, sure, but you have to realize, while this is an emotional subject for many people, it's likely an emotional subject for her as well.
She said something smart-ass, it was received poorly, she retracted it. That should have been the end of it.
I think it's better they just ignore the whole topic. Asking a modern white American to address race is like asking a Victorian society lady to address sex. Not only are we unwilling to ever talk honestly about it, I think we're in such a deep twisted state of denial that I don't think we're even capable of doing it anymore. Well some are, but they're usually immediately silenced by the freaked-out white majority.