I liked 75/25 because overtime any whales share would be diluted(they are giving out more rewards than they take in).

This wasn't what actually happened though.

Massive delegations to bid bots and paid votes meant that whales got more like 90% (combo of curation and the bids) and legitimate authors got almost nothing (sure you got 75% as an author on paper, but to get any real votes you had to pay for them in practice, giving most of that back).

The change to 50/50 was part of a package meant to discourage vote selling (including bid bots) and encourage more merit-based voting. And it somewhat worked (there is still some vote selling, but it just isn't as rampant). That included downvotes, the curve, and switch to 50/50. Perhaps only downvotes is enough, but perhaps not. I'd rather change one thing at a time (in this case the curve) and see how that goes first rather than rip out all of the changes that actually worked and bet it all on downvotes alone being enough to keep vote selling from growing back into a bigger problem.

Staking might be a factor too. I mean if staking is a big draw and it keeps the price of HIVE higher, then authors benefit that way too. Personally, staking isn't really something that gets me excited, but I recognize that others feel differently.