Obviously this is a complicated situation with many parameters in the equations which all have knock-on effects which are hard to predict the outcome of accurately. For every argument here I can see a counter argument and there are valid points to be made on both sides. I see flexibility being the solution here - which could mean having the payout split created dynamically from the settings of individual witnesses, as suggested here already by @josephsavage - or it could involve the introduction of Steem Communities as was basically promised way too long ago and which have not yet surfaced. Communities can support a variety of independent settings, such as a difference in split of curator/author rewards - so once those go live, in theory, the default split becomes less significant.

I can appreciate the concern that big stakeholders will be better rewarded through upvoting others, however, here's what I see as being the argument in support of that outcome:

Steem is not an attractive investment compared to many other tokens, primarily because it's value continually drops due to inflation. From that perspective, Steem is like a leaky sieve from the perspective of investment. It is only viable if you either expect it to explode and compete with Facebook et al - or if you intend to be active on the network and make many of your own posts. Since there is only so much time in the day and so many things to post about, long term investors are pretty much forced to either continually make pointless posts to not lose the value of their investment or just pull out. This means that we see lots of shoddy posts at the top of the lists and it is discouraging to most users - plus totally invalidates the entire proof of brain mechanism that underpins the entire Steem concept. So.. by giving more rewards to curators, long term investor's lives are made a bit easier. You can always say that these people can just leave and we will only then have people who are here for the content, which is fine, but plenty will not leave and if they do - in enough numbers - the price of Steem drops even more.

It's fine to say that Authors can't afford to make content when they don't get nice payouts - but huge numbers of people (including me) have been making content totally for free for over a decade... So while, as an author, I have empathy for that position, the reality is that something is better than nothing.

For me, the bots are a bigger problem than the whales as they totally depersonalise and invalidate the underlying mechanism of post valuation. They remove the competitive aspect that has people battling to be the 'best brain' .. And so, much of the excitement of Steem is gone as a result of their use. If increasing the curation payout has an effect of chilling support for bots then that is a very good thing - though it remains to be seen if they will.

Personally, I am open for experiments - so I'm open to seeing what effects a split change has, it can always be changed back again. I personally would have gone for 66.6%/33.3% (or similar) as a middle ground.

I have said almost since the beginning that Steem is not being evolved quickly enough and I imagine that it is quite likely that we will see another team take over from Steemit Inc. in the next year or so - maybe the Steem Engine team.