How about the fact that zsh enforces that you spend a certain amount of time per day just contemplating your existence:

    % time zsh -c exit
    zsh -c exit  0.22s user 0.21s system 97% cpu 0.436 total
    $ time bash -c exit
    bash -c exit  0.00s user 0.00s system 83% cpu 0.004 total

Typing too early will just blackhole your keystrokes, of course, so no cheating!

Or how about how when using an RPROMPT it makes copy/pasting stuff out of the terminal infuriate your IM buddies?

:)

Actually these are downsides, let's try fish instead, maybe?

    % brew install fish
    % fish
    zsh: correct 'fish' to 'vis' [nyae]? GRRR