I don't think it's overrated.
Depends if it's your cup of tea or not. If you don't care for their mainstream type of music, then of course you're probably gonna be like "wth is this crap".
And if you just try out only a few people, and give up on their music, then you're going to miss out.
There is an amazing pool of talent and ingenuity in Korea, as there is in any country. I feel sad that some people regret that there is a "boom", and that music from another country is starting to get more recognition.
You should be happy that people are "diversifying" and trying new things.
As for BoA. I don't like a lot of her music. For me, it's boring, same old same old pop, and her voice can get annoying. But I
her dance tracks...and Hurricane Venus just happened to be in Korean. If it was in Japanese, I would still love it...so I don't see why it's sucky.
I could see how some people could like...specify more, and say "so and so is overrated" or "their mainstream pop scene is overrated"...but then it's still all based on opinion isn't it.