Hi Mapu -
That has not been our experience since buying 2 Rimowa Topas carry-on cases in 1994.
Quite the contrary, we find the alu. cases lighter than others, and can easily pack a week's worth of light clothing, an amenity kit ( Rimowa, of course) and small personal items.
But you do make a good point about overloading carry-on, which many passengers can do, especially in Winter.
Cheers,