[disconnected]

> I don't understand it either [...] Esc is even on the same side as the keyboard

Put your hands on the keyboard home row (where they belong).

Try to reach esc without taking them out of there. Hurts, don't it?

Now try reaching caps lock. Much better, right?

That's why.

Caps lock is useless. Esc is extremely useful (for vi users). So we get rid of caps lock and put something more useful there.