I'm not convinced that <PERSON> plan is entirely evil, so your premise may be flawed. (Well, clearly the means by which they go about it is evil, but the characters may feel it's justified to right what they perceive as wrongs.) We don't yet know enough about what the ultimate goal is to say one way or the other. She's talked about undoing all the bad things that E-corp has done, so it could end up being that she (or China in general) is the hero in the end. We don't really know how <PERSON> ended up working with them and arranging the whole plan or what the whole plan is.
The other thing is that the antagonist needs to be an entity that can plausibly do the hacking that needs done, and that also plausibly would have a reason. Since the action takes place in the US, that means finding an adversary to the US or at least a US-based corporation. Likely candidates are Iran, North Korea, Russia, and China. Iran and North Korea are the least plausible of that group, considering that the plot requires the US to concede to allow the antagonist to annex the Congo (or any other nation for that matter). They also need a way for characters from that place to be able to freely move about in the US without suspicion. 45
That's probably difficult for someone high up in the Iranian government and impossible for a North Korean.
So that leaves Russia and China. Back before it was revealed in real life that Russia was attempting to directly manipulate the US elections, China probably seemed like a more probable candidate and the writers probably thought it would be an easier sell.
That said, you are right that they don't appear to show any East Asian characters in a positive light. It's unfortunate, and is probably for the same reasons that other shows do the same thing - partly ignorance, partly biases (conscious or not) on the parts of the writers and creators. This is an ongoing problem in Hollywood, though there does appear to be some movement towards fixing it. Recent shows like Crazy Ex-Girlfriend, for example, show a hunky Asian man as the romantic lead. And a few years ago <PERSON> played the male lead in the TV show Selfie. Maybe this is the start of something bigger? We can hope.
As for why no critics mention it? Well, some have, both positively and negatively. It just depends on where you look. 282