Well, from a business point of veiw, that tool has not hampered sales of the cleaners and it must cost pennies to mass produce. But as a floor tool it's far from the most effective - particulalry on carpets.
That floor tool that is still supplied with the Dyaons today is pretty good. However when I try to adjust the setting from carpet to hard floor on a hard floor, the suction is so strong that it is actually impossible. I tried this, and as a result the plastic bit you put your foot on broke off on my DC05