The 15 minute curation tax timer are one of many other secondary issues that deserve another look at, but they're not what I call core economic issues, that is I don't believe they'll materially affect the content indifferent voting behavior problem we have
Curation is about incentivizing stakers to actually vote on content which they believe others would agree is appealing by rewarding them for it. It's true that established authors can become very 'sticky' but this is also true for all other platforms. It can incentivize people to build a long term reputation.
I also think that mobility away from established authors to uncover new talent is a good thing. Some amount of free downvotes is one mechanism that this can be done, as people will be more liberal in their use to bring down posts that are overpaid, and curators over time will learn this and adapt their behavior.
I am, of course, sensitive to the downsides of additional downvote incentives. We will try to work with a moderate amount of free downvotes, just sufficient to keep stakers mostly honest and no more. There are costs to all these measures and the challenge is to find the right balance