As someone not in the industry, I don't understand why anyone should use a market order. I don't even see what the downside would be to outlawing it or why professionals would ever use it. Particularly ever since the publicization of "flash crashes".

Furthermore when I place a limit order close to the market I almost always see the price move away immediately, and I can't help wonder if somehow it's being manipulated to try to get me to chase it. If I log off and wait, it frequently gets executed after a few minutes.

I was chagrined to find that a limit order I placed yesterday was partially executed. Of course I should have made it "all-or-none".

People say the market keeps getting more efficient due to high speed trading, but to me there's something lacking in the definition of efficiency. If "the market" isn't stable enough for a reasonable human reaction time, that's worse, not better.

My thoughts aren't well organized right now, but basically I feel like there's something about the ignorant raging that one reads about HFT that points to a real, but subtle problem.

Edit: Look at it this way: I don't have liquidity, unless I am willing to place a market order. But the market is a leaky abstraction - I'm potentially hanging myself out to dry with a market order. On the other hand, with a limit order, I do not have liquidity because other people trade faster than me. As I described, I tried to sell a certain amount and it ended up taking 15 minutes and only executing 1/5th. So an efficient, liquid market that is supposed to be _better_ seems _worse_ from my perspective.