it will hurt some day trading shops, most places were probaby charging $15/1000 shares, while the "bullets" would only cost a firm about $3-$5 for a 1000 shares, imagine a making a profit of $10-$12/1000 shares !!!
used to offer both retail and prop bullets at my previous firm...margin is 10% aggregate exercise price(10% strike*shares) it used to be much higher...since strike is usually 20% above price, margin is more like 12%m, still really low...