I don't agree that curation rewards are required "instead". I've been very doubtful on anything not involving downvotes as as a core focus (routinely embraced and used as a opinion-expressing vehicle and not just for "abuse"), or a complete profound redesign, ever working and even with downvotes I'm still not convinced it will work. I don't see a strong argument (that doesn't involve a great deal of wishful thinking) that voting to distribute inflation ends up with anything other than distributing according to stake or distributing superlinear with stake (which tends to push anyone but the largest toward the exit)

That said I do agree that the 4x (in fact higher) is a problem that will probably contribute to failure unless addressed and I've been saying that ever since 25% was put in place (over my objections).