Yes, HFTs profit from other participants because they are selling a service: liquidity.
There have ALWAYS been sellers of liquidity. Due to automation human sellers have been replaced by computers that cost far far less. So the cost of liquidity has gone down DRAMATICALLY. Spreads used to be a quarter (or higher). Now they are a penny. That's a 25x reduction!
Here's the chief executive of Vanguard (the world's largest mutual fund company) talking about how HFTs have lowered trading costs for their clients:
http://www.cnbc.com/id/101615521
If you slow down cancellations or otherwise try to slow information flow to HFTs you will simply raise their risk which will force them to raise the price they charge for selling liquidity by increasing spreads.
Stop thinking of HFTers as parasites and think of them as service providers and you'll have a clearer picture of reality.