This one: Or are you concerned with how the curve will initially decrease rewards on low rewarded posts?

Here is one use case that the new curve renders less functional, but there are many more:
I run Punday Monday every week. People write puns on a given topic, and I reward the successful puns with my vote. It's a tiny bit of positive on the chain, that takes a tiny bit of effort, and that is rewarded with a tiny bit of money.

Will they all stop now? I dunno. I think they enjoy it enough and have learned how to do it, so they might keep going. But I also think they started because of the promise of a little change in their pockets. That's the promise of Steem.

So, my understanding of the purpose of the platform is: it's a social media platform and a blogging platform where user likes have financial rewards. Maybe it is other things, too, but that seems integral to the premise.

The whole point of this change is to change behavior, so I'm not sure why you don't think the rewards curve change might even impact desirable commenting behavior.

The "where user likes have financial rewards" part is currently true! Yippee! My largest concern for EIP, is that the plan forgets or ignores the needs of the average user, who isn't trying to maximize returns, but who is rather trying to use the platform as advertised.

Editing to add: nowhere did I say that EIP will "stop comments". I didn't keep saying it. I didn't even say it once. I just want to include this addendum because I'm not sure why you say I said that. Maybe there's a misunderstanding here. I think EIP will have a net negative impact on regular, human, positive behavior, including comments, but I don't think it will stop comments entirely. I don't even think it will destroy Steem. It'll just make it incrementally harder to be a new or poor user.