I think that is actually a totally fair way to look at the show. The moral implications of Kotaro's actions are immense and dark. Also, the way he more or less threatens them with society's reaction to zombies in order to become idols is extremely manipulative. I can totally understand why those aspects of the show would turn somebody off from watching.
For me, I have been enjoying the show after basically accepting those bits as the needed bits to establish the premise and then moving on. Namely, the premise of a group of zombie girls becoming idols. After the first couple episodes, they aren't really brought up any more and the girls are all acting of their own will. They are even capable of doing the makeup on their own without Kotaro by the time you reach season 2.
That's a good point. When I am making okonomiyaki at my table, it is just for me. I am not making it for the person that sits at the table after I leave. At the very least, I don't think gyoza vouchers are an acceptable form of compensation in Japan (how do you pay taxes on gyoza?). It's fun to riff on, but overall I have been really enjoying this series so far.
As for random downvotes, it happens everywhere occasionally. I suspect it is people seeing things they might not like when they browse the "all" feed of their instance rather than "subscribed". They are just random internet points, they don't matter at the end of the day.