DesertTortise,
I agree completely with your position, with one exception, robot vacuums may well become a game changer, but they aren't there yet. They are moderately effective on surface litter and hard floors but have neither the capacity nor power to deep clean a carpet and run time is still fairly limited. I have a Roomba and it does a lousy job in small rooms with a lot of furniture and often gets stuck under the edge of the sofa because it fits under some areas but then can't find a way out of others and will get stuck under a bit of trim or my favorite spot to find the darn thing, under the front of the lazy boy, run up part way on the base, and then it can't get enough traction on the broadloom to back itself out. They have improved tremendously, but still have quite a way to go.