I agree. I've always thought of HFT as a way to let liquidity flow between exchanges, with a payoff equal to the degree to which the inter-exchange spread has been decreased. If the inter-exchange spread is wide, there is some value to be extracted from that spread, and HFT provides the (in my opinion) valuable service of extracting that value, making the market more efficient as a whole. The more people that are competing in that market, the smaller the value the HFTs can extract, until the actual market participants on the exchanges are only paying fractions of a penny for the privilege of buying shares "originating" from another market that has higher liquidity. I can't really see how this could be a bad thing (given enough competition).
