That really surprises me. I have been a bit more careful since the cancel fee was instituted but I have cancelled orders. So far I have paid a total of 40 cents in fees. I make between 1 and fifteen trades per day. It may even be helping my entry points but I'd hate to give "them" any credit at all.
It may not pay to daytrade them and play MM any more. That game is over for me. I only really scalped if I had a lot of time on my hands anyway. I have changed all of my orders to day orders and I just get on the inside and wait it out. Sometimes I get filled, sometimes not. The savings on the spread (SPX opts) more than make up for the missed fills and any cancel fees (only one so far). I think the effects depend on your personal style. You may have to change your methods. This fee was intended to alter the behavior of individuals with certain styles. Sounds like they have made it less worthwhile for you to do what you were doing.