Arbitrary decisions like "we've only got 20 buttons to use, or the front
panel becomes too busy", leading to "I know, let's leave off the numbers,
and just have 10 min/1min/10s buttons" type decisions (meaning that for 7
minutes you've go to press the button 7 times, not just "700") are just
annoying.

Agreed. When purchasing a microwave, having a keypad with numbers, rather
than +10, +100, etc, is an absolute requirement. I simply won't buy a
microwave without proper numbers.

Christian.