You bring up a good point, that votes on posts and comments should have different structure.
I think with 75% curation reward people will be more likely put in their live savings into steem instead of other investment options which in return increase the price of steem and more votes for authors. At 75% curation there is no need to invest in bidbots. In this case investors will be more interested in steem working organically because it will increase the the value of their investment.
But this will never happen. People are focused on short term gains.