I come from the cut throat world of 'internet promotion before steemit' - which is a world where people think nothing of spending many thousands of dollars a month just to try to get seen in the google search rankings - partially because of that I can just write off the cost of bots as a type of marketing cost that is intended to generate a return and usually they do - which is part of the issue here.. The bots are often profitable even without them generating new votes.
I see the unfair advantage as being the existence of an imbalance of wallet sizes ultimately, which is true and I suppose though that the counter argument is that the wallet imbalances will exist with or without bots.