I do find validity in the argument put forth by @kevinwong that the extreme ratio in baseline profitability of 4-1 between self-voting and curation deserves addressing and the system would benefit from addressing it (which is what the 50/50 change does, by reducing this ratio to 2-1). It is an element of shifting the economic incentives toward useful curation outcomes and away from the useless self-voting extraction outcome. (Note: "shifting" does not mean, by itself, "fixing", it means just that).
That said, I'm not personally against just the downvote change and I think it would be helpful on its own.