I agree with all you have written, but there is a way to zoom in or out without using your other hand: use your lips. "Muaa" zooms out, and "auum" zooms in. This will make public transport journeys more interesting (for the others).
I probably am. I spent some time in northern Europe, where the temperature would go as low as -25°C, around the time I stayed. I was loath to deglove my barely warm hands, and used my nose instead, for some basic operations.