It seemed like the Creator had a plan for future seasons since there were little hints to things building up in the background of the first season so I doubt there's no plan and that they're just milking it. Of course it's hard to know if it will be as good since lots of times first seasons are good because they developed the idea for a decade then when there's an opportunity for a season 2 they're not as prepared on the details.
The entire premise is already exposed, and the story complete. Any attempt at a second season is just a pointless cash grab that completely ignores the message of the show to begin with.
Thats the best thing about the foreign adaptations on Netflix. Hollywood isnt involved, the formulas are different, the bars of acceptability are different, audience expectations are really different.
I'm assuming that the season 1 MC will only be minimally involved, probably a couple of scenes at the end of the season. The teaser trailers didn't show any new scenes with him, he was only badly edited in for a second.
It was actually incredibly powerful. The first episode or so is dumb in the way that only Korean films can be. But if you allow yourself to be sucked in, you're in for a wild ride. Not everything about it is good, and some of it is a bit on the nose, or too gratuitous with the violence, but the message in the final episode is worth watching the entire series.
Popular things can still be entertaining, just look at the original Star Wars for instance. You can always give it a shot, sometime. Also, expectations can sour an experience so try to be open and everything, especially considering where you're coming from.