I don't have an opinion on the main question, but I would like to note that the helicopter example proves nothing. With a helicopter in autorotation, the rotor is generating lift, but the weight of the helicopter is greater than that, so the helicopter falls. The lift, though, tries to move the helicopter toward the curved side of the blades (i.e. up). The argument about the idling prop is an argument that the drag from the prop will try to move the plane away from the curved side of the blade (i.e. backward). So the helicopter situation would be analogous only if the helicopter were upside down. I don't think you could talk a full-scale helicopter pilot into trying that experiment. Compare a plane flying straight up (or hovering) with the same plane, still vertical, and a stopped engine. The plane with the stopped engine will fall, just like the helicopter. This doesn't show that the prop was producing drag, it shows that it was producing lift (i.e., forward motion).

As for help with landings on a short field, the plane shouldn't be nose-down on final anyway, so drag is unimportant. If you want more drag, get the nose up. What the original questioner needs is a plane that can fly nose-high without stalling. Diving toward the field makes your landing run longer, because it builds up speed.