A long time ago, a TV ad for a detergent for washers demonstrated how you could squirt tomato ketchup onto a dish towel, then tie it in knots before putting it into the machine, and it would emerge spotless thanks to the power of this powder. Coluche, the much-loved French comic who was killed on the French Riviera in 1986 when his motor-cycle collided with a truck, used to point out that it was time-consuming and wearisome to tie knots in all your dirty clothes, and then have to untie them after they're washed clean.
For reasons of a similar kind, I would be reluctant to invest in the suitcases shown in the following ad:
I've grown accustomed to suitcases on tiny wheels that you can drag along behind you in train stations and airports. Besides, I'm getting on in years. For me, it would be a rather strenuous burden if I now had to master this amazing new way of moving around with a suitcase.