[kumjhbfa] Large type keyboard

Draw letters on keyboard keys as large as possible.  Is there any good reason not to do so?  Maybe to save paint.

Obviously, large type is useful for people with poor vision, or in poor lighting conditions.  It is also more robust to paint becoming scratched off and letters becoming difficult to read.

Unrelatedly, possibly useful for learners of a language is to have both the upper and lower case versions of a letter on the keycap (and also alternate letterforms e.g., two- and one-storey a and ɑ).