Another factor is that curation rewards generally favor users who already have a larger stake in the platform
This is true but with linear rewards the effect is greatly reduced. It's certainly the case that more SP generates more rewards, which is natural, and probably okay (and doesn't really promote a 'rich get richer' effect), but to what extent it has a higher return on investment, I don't know, though it is almost certainly much flatter than before.
As a first step I agree with shortening the reverse auction (with other benefits), and we can see how much that changes things. Some part of the effect will be faster bot votes so the aggregate shift may not be that much, I don't know.
Another intermediate step I would support is enforcing actual 75/25 instead of dynamic. When the reverse auction reduces curation rewards on a particular post or comment, instead of giving them to the author, put them back into a pool for other curation, so the mix of author/curation always stays at 75/25 (or whatever specified mix).
One thought to offer in closing: If 'most reward' doesn't correlate with 'good' (value adding) content as you suggest, then posting rewards are no less dysfunctional than curation rewards (i.e. it means content that isn't 'good' is being rewarded). I don't see that as a particular reason to favor author rewards over curation rewards, do you? At least increased curation rewards has the potential to improve this situation by incentivizing more effort on curation. I don't see where more author rewards do anything to improve the dynamic of bad voting. The latter seems almost impossible.
The reduction of the early voting penalty should be the easiest to pass since it isn’t very controversial and it would be an easy change.
The variable curation/author split that which can be set by the individual platforms (or even the users), rather than being hardcoded to 75/25 seems like a really interesting idea too. There are details in @jesta’s reply to the recent steemitblog post. I wonder if we can rally support around that.
Yes, clearly the latter is a more significant change in terms of implementation, maybe controversial, hard to say. But yes, very interesting idea. Overall I agree with your assessment.