As usual, tales of rigged markets and front running are equated with HFT, and modded up +5 by people who need to step back and take a deep breath. Please ponder the following points and think again.
1 Front running is what we call it when a market participant gets a peek at orders before they go to market. You could send your orders in on a post-it note on the back of a snail, and if that participant sees and acts on them before they go to market, that's still front running.
2 Flash trading is what we call it when an order is shown to a market participant for a brief moment of time before they go to market. Sounds like front running, right? Except that (at least for DirectEdge customers) you can flag your order to not be subject to flash trading. Why would anyone voluntarily subject their order to flash trading? Who knows - maybe they get a break in commission - the point is they can turn it off.
3 Rigging the market may also include self trading in an attempt to boost apparent volume at a price, or quoting prices you don't intend to be filled on to goose the market. Both of these practices are already illegal and well policed by the exchanges and the SEC.
4 The "liquidity" that everyone pooh-poohs is part of what makes things cost what they do. Introduce more bid-ask spread in the commodities markets, and the costs will go up for pretty much everything: bread, milk, gasoline, etc. HFT helps liquidity because it reduces the time for cheaper prices to percolate around the market.
5 HFT is there because the markets are largely FIFO, and the markets are FIFO because FIFO is unbiased. Can you think of a more unbiased match algo? Lots of people put forward some sort of time bucketed system, but it doesn't solve the problem of who gets filled when there are more buys than sells in a bucket or vice versa. Nor does it solve the problem of cross exchange trading where time buckets are not likely to be synced, and people deal with it by increasing the bid/ask spread they're willing to quote. (See #4.)
Sometimes, it really is more complex than "She's bought and paid for by HFT". Plus, if you can't bring yourself to take off the tinfoil hat, you might consider that opponents of HFT (like big banks) are precisely the ones who benefit if HFT goes away. Now back to your regularly scheduled screedy goodness.