In my experience shoe mold and quarter round have always been able to be used interchangeably. I always thought it was simply "the look" that one was after choosing one over the other. The smaller shoe mold will usually follow variances in a floors surface a little better than quarter round in my thinking.
With today's base boards getting smaller and smaller [in thickness] and the requirement of expansion gaps at the walls an additional element (shoe mold or quarter round) is becoming more and more necessary to guarantee the hiding of the expansion gap. With laminate floors and their ability to shift (if not installed with hidden stops) the wider base treatment is almost becoming mandatory.
First I've heard of the "dust" thing. A basic truth of course, but I doubt that's why shoe mold is made available as an option.