Where @edicted says "All curation should be optional" then I agree. But I think that it should be at the option of the voter, not the author.

The problem with curation being at the discretion of the author is that it creates a race to the bottom. Some (large) voters will let it be known that they will only upvote posts with high curation rewards for themselves. Or naturally, posts with higher curation offered will do well. Which forces authors to compete for attention by offering higher and higher curation until they all (or many) are reaching the maximum curation possible. Which means voters who want to give 100% of their vote to the author, or 75% will not be able to.

Also with a curation slider for the author, posts with very high curation offered will do well, perhaps very well, even if they are poor quality. The incentives are misaligned.

I really think that there should be no incentive to vote on particular posts, which means people are free just to choose and promote the best content, which is best for Steem.

I disagree with the curator choosing the amount of curation/author rewards to give for their vote. Those who want 100% would thereby give no rewards to an author, and take them all, simply for voting posts. They wouldn't even have to go through the task of creating a post to vote on themselves

Currently any voter who wants 100% of the value of their vote can simply sell their delegation to a bid-bot. Or vote on an alt. Or join a circle-vote. Or use the vote-swapping services which now exist. Pretty much all of these damage Steem, particularly bid-bots, as the end result is the promotion of poor quality content on trending.

It would be much better to bring those passive investors back into manual curation. Or as an alternative to have them passively trail "trusted curators" who find the best content to promote the blockchain. If they can set their own curation rewards at level they are happy with and rely on someone else to do the actual finding of content then their SP can help to promote the best content on the blockchain whist retaining their desired rewards and passive status.

I would add that if blocktrades, or another whale, were to upvote my post for $50, but only give me 10% author rewards, or even 0%, then I would be happy with that. As long as it got me $50 of visibility on the post payout then it has value. With more visibility more people would see my post. Some of those readers might give me a percentage of their upvote too. Some might just give me more visibility.

As a content creator more followers and more visibility is the starting point and would give me more opportunities for advertising / sponsorship etc. Any author rewards that come with that increased visibility are nice too.

Perhaps this approach brings Steem closer to a combined youtube / patreon structure of rewards. However I would also expect that many Steem users would remain with more balanced levels of curation, so we would have a mix of the three.