Buttons are very familiar in the real world. Your computer keyboard is many buttons with single character labels actually on the buttons. Elsewhere the labels contain more characters and being larger are placed beside the buttons. But stop and think. Why do buttons have to be small, too small for their labels? There are two reasons, wear and jamming.

If the label is on the button, it will be worn away. There are techniques for permanent labels, but they are too expensive for usual production runs. Only key caps have the volume to benefit.

More subtly, buttons have the same problem that draws and sash windows have. Narrow, deep drawers and narrow, tall sash windows work fine. But a wide draw or a shallow sash window requires care to get it to work. There have to be two handles or finger loops so that you can guide it and keep it straight. Under the space bar of a computer keyboard is a mechanism to do the guiding for you. To avoid the need for mechanisms that would push the price up, a button cannot be much larger than its depth.

Buttons are a cheap and nasty way of getting round mechanical problems in the physical world. Ideally one would just press the label.