Human behaviour won't change. Automation will increase in the future. Content creators only getting 50% will de-motivate curation. Since you know that if you curate most of that value will go to the curators that leech off a piece of original content. The original content creator invested more energy and did the largest sacrifice.
Therefore they should get the highest reward. There is no incentive to curate new content if most won't go to the real creator. If Stake holders doesn't trust content creators then the network is broken. Since content creators are the future. This would only make big stake holders get more wealth. And a Steem middle class would be further away from reality.
I agree that human behavior generally stays consistent for individuals, although varies widely among them. I do however disagree with your logic. Isn't it the curators votes that ultimately determine the value of the creators post? It may seem valuable to the creator, but generally rewards for just creating and posting are rather small. It is the cumulative upvotes from the curators that give the post it's real value by consensus, not just what the author thinks it is worth. Hence by giving more value to the curators vote, they will tend to vote more often and at a higher weight on the good posts, making them more valuable than the auto-voted spam posts. Or at least I believe that is the intent of the platform. It is definitely what is needed to help reduce the low value posts and keep people interested. If there continues to be an overwhelming amount of garbage posts, people will just leave the platform for something more interesting.