They should make it so you only hear bahs (or wahs?) when you are small Mario. Encourage cleaner play.
Or only when you're NOT small Mario. Encourage dangerous 1-hit-death hardcore play.
And talking of Athletic themes. If you really can't stand the BAHs. DON'T LISTEN TO THE ATHLETIC THEME FROM NSMB2! It's 100% BAH!
Actually that's an accordion synth, not "bah"s, if you listen carefully.
However, to spite GAF, I think it may have been intentional.