Proof of Brain I feel is somewhat of a oxymoron in regards to a social platform that 'promises' reward for content. Perhaps the maximizers and sellers are the ones proving they have a brain as they sell out of Steem and buy BTC. The problem of course comes when what they are buying into is another position in the status quo.

As far as the bots are concerned, they definitely do decrease the level of engagement and unless one has very large stake, I think for the most part they should be limited to supporting a small pool of interesting authors rather than looking to maximize return through curation. OF course, that is crazy talk because from the moment most step on, they want to maximize their returns.

I can't really say how much it affects price because for the most part as far as I can see, price is not connected to anything other than who has the money and will to pump or dump a coin.