They're ranked by stake, so the big guys make the most. Absolutely no difference to what we'd have here.
You're right about the nodes. This is a technical necessity though, and setting one up is as simple as keeping your wallet open, no effort at all. They need this to have block production decentralized, which is solved on steem by the witnesses.
You also need to see that vote selling already allows for cold ROI, with all the negative side effects. It can't get worse than it is right now.
Valid points ..but let's parse this statement a bit more
In my understanding not everyone makes the same % ROI ( big guy vs small) so the smaller staker gets very low % ROI hence there is an element of market risk , albeit it's more of a winner takes all.
What is proposed here is everyone gets the same % ROI as cold return.
If every staker gets the same % ROI , I concur with your point and find both situations to be quite similar.
Bid bots still operate with a market risk that tomorrow any of the UI may decide to ignore the posts upvoted by them so they have an incentive to keep adapting with the ecosystem.
I don't know any PoS coin that gives a higher return to big stakers. The percentage of staking coins you hold usually defines the percentage of blocks you create.