Modified keypad keys

[Per Starbäck]

"(emacs) Function Keys" says:

> By default, Emacs translates these keys to the corresponding keys in
> the main keyboard. [...] Note that the modified keys are not
> translated: for instance, if you hold down the <META> key while
> pressing the `8' key on the numeric keypad, that generates `M-<kp-8>'.

I wonder what the rationale for that is? Would there be drawbacks in letting
<M-kp-8> behave as M-8 as long as there is no explicit binding for <M-kp-8>?

The reason I wonder this is because I recently watched a student of mine trying
C-x <C-kp-add> after reading about C-x C-+.