It comes down to providing the right balance of incentives. At the moment passive income (vote selling, delegating to bots) is higher than contributing to the platform through curation. It is roughly three times higher. Adjusting curation rewards up to somewhere closer to passive income will provide incentive for users to be active. 50/50 split between authors and curators has been suggested. I am not convinced that will be sufficient to pull delegation from bots. I think 75% curation will be effective if combined with several other changes such as separate downvote pool and SBD included in payout to curators. Someone mentioned 100% curation rewards but I believe that would kill the incentive to create content.
A much higher curation reward will most likely increase the incentive to frontrun bots, thus reducing bot curation rewards. Frontrunners could be earning well over 100% of rewards per vote, which will be higher than any bot could offer. If bots are only getting 2/3 of the curation rewards and offering a positive ROI, they could be earning less than the 75% curation reward. The incentives to operate and delegate to bots will be greatly reduced.
Downvotes would be more effective as well as the downvote will reduce rewards to the curator. Curators are more likely to upvote content they feel will not be downvoted. This is another reason why downvotes should not penalise the downvoter. At the moment downvoting is close to non-existent. If downvotes were free, i.e. separate downvote pool, people would be more likely to use them.
Thanks for your comment. It is good to see another perspective on the matter. I think this response covers your other comment as well.