With those changes, in my opinion, users will just move from delegating to bidbots to selling the "right" to vote in their name to services like minnowbooster and smartsteem.
Also many users enjoy the passive income that comes with the delegation. Maybe you are focusing too much on the social side of steem, failing to see it as a platform for many other services / businesses. If so, private chat on steemit would be a great start (it doesn't have to be on blockchain).
Voting services are not necessarily bad to the extent they vote on content in some sort of intelligent manner, which is what these changes would encourage (otherwise downvotes and poor return on curation rewards is the penalty, and even if they do pay this price, the rest of the system, i.e. people doing things closer to as intended, benefits from that penalty). A voting service that takes care as to what it votes is called curation.
No voting services intent on financial matters care at all about content. No tweaks to rewards curves or curation splits will change that. Any financial incentive to curate is financial incentive to corrupt curation for profit. At best some curation services like @ocdb seek to reduce financial manipulation, but they cannot compete with stake.
Eliminating incentives to corrupt curation is possible, and will solve the problem with facility and simply.
Entirely correct. The idea is to get bid bots to alter their businesses and compete over some form of curation that isn't mindlessly supporting the highest bidder indifferent of the actual content. It just needs to somewhat track content based on the its predicted general appeal for the system to work. Some amount of free downvotes are likely needed to keep everyone honest