I think people aren't giving flechette cannon /D enough of a fair shake. It's one point cheaper than an Ion while still doing a damage unlike a tractor. Also against some ships that stress is going to screw them more than a single ion token would, mostly large ships and ships with turrets.
Shuttles and Hound's Tooth's that are in a great position to stop now won't be able too, and that doesn't even count what a stress can do a brobot in a bad position. Your opponent will burn everything to stop that stress if it means they can't s-loop next round, which will open them up for your primary.