"economic incentives" apart and without going into all those details (techy stuff) - if it is really truly seriously a matter of making a change in voting behavior from "content indifferent" to "Content Attentive" and Interested, about caring for Quality of Content (or at least about bothering to as much as VIEW that Content from inside the post - not from "outside", just its title in the Feed list)...
then there is quite easy and simple solution to accomplish that - IF Steemit Inc. would actually care to do so (yeah, yeah, and if Witnesses "come to consensus" etc). that solution I have explained here. it is basically, in brief: make the Upvote button visible only for those who have bothered to actually Open and Read that "Content" (post) ! :)
bots would "get tired" to open all those links, scroll down to the end of post, find that Upvote button -- all that just to press it to complete the so called "Curation process". (or perhaps bots can't even do all that)

that would help to achieve what you are trying to focus on:

being able to influence content by voting

if no one is able to press Upvote button at all from "outside" (from Feed List), but only from "inside" (from within the page of that post) - THAT would certainly INFLUENCE content by voting! and shift the voting behavior from "content indifferent" - to Content-Reading-Compulsory.

however something tells me that present state of affairs - quite perfectly FINE not only for the System itself, but also for all the "Investors" / "Stakeholders". whose main (or only) concern is not the Content itself nor its quality - but the ROI. (and for System - the long-term lock-up of the capital within itself; aka "High Yield Corporate Bonds", the "Mutual Fund" of all those SP "Stakes" combined)
Upvote button easily accessible from "outside" the Post (i.e. without need to open and actually Read its Content) and available for bots or anyone to just press it without need to click the Link (title) of the Post. therefore why bother to do any more than just trivial basic action of "pressing Upvote button"?
since System doesn't require anything else at all and doesn't care at all. then why should care all and any people who come here to Earn? (especially those who has Invested, especially quite a lot!)

so called "Active curation" (LOL! what a term! like "active pressing of Upvote button"? bots are good at that! :D) will not happen - because System doesn't care about it, doesn't require or demand it, because it is not important for it to generate the profits and to sustain itself. It keeps "minting" more and more new tokens "out of thin air" (as Taraz rightly mentioned it some time ago :) ), so, main thing of it is - "generation of connections" (aka "links from clicks on Upvote button" LOL :D) and the fact of "content discovery" aka "Curation" (= which Upvote buttons under which posts titles in the Feed List are pressed and which are not). as long as such "Business" continues - it is quite alright for the System. it is NOT at all necessary nor important to even READ the text inside - what to speak about the evaluation of Content Quality (what is normally meant by Curation).

That's why Stakeholders are being bluntly straightforward now - in making proposals of such ideas ("Lock up Stakes") - so that they don't even have to bother with such a silly nonsense as ANY kind of "Voting" at all. just Invest (= "Power Up"), "Lock Up" and get increased rewards for that (for NOT selling their votes otherwise) aka "Passive Income". funny though that at the same time "improving content" is mentioned at all. because WHAT "Content" or its quality is of any interest at all - if person is fully satisfied with "Earning on Autopilot".

Passive can stay silent and invisible...

yeah, why not! :)
desire to care about one's ROI is understandable. but there is no need to cover it with some sort of "caring about content improvement" and about "voting behavior" LOL