@OP - the problem isn't with kumon. It's with the parents that use it.
It's like the parent that went on about how her DC was struggling in maths in Year 10 because kumon hadn't given the DC a proper understanding. The DC was in Year 10 and was struggling and of course this was an example of the failings of kumon and had nothing to do with the school she was in.
Then there are the parents who have an either or approach . You either get the DC to study 20min a day OR you get your children to bake, go to museums and do kids stuff. Why does it have to be either or? Why not both? DS did kumon and still did football, swimming and music stuff.
We chose kumon because we didn't have the time to trawl the Internet for a constant source of free material. Buying work books wasn't an option either. Do you know how many books you need to buy in order to generate enough material for daily homework sessions?
If you don't think kumon is for you then that's fine. As I said above, its not for everyone. There have been threads on alternatives to kumon. Something called Lip Mc???? has been mentioned. I suggest that you look at your DC's abilities and what your aspirations are for your DC and take it from there.
Although it may seem like it, there is a large contingent of pushy parents here. It's just that the let children be children brigade is a bit more vocal. So don't let anyone convince you that you are a bad parent just because you have academic aspirations for your DC.
Take it from a parent that has been there and bought the T Shirt, children can be children and still be pushed academically, if not with kumon then with something else that works for your dc.