You see wind instruments outside of orchestras all the time though. The main reason for the domination of guitar and piano is economic: you can play more notes

You see wind instruments outside of orchestras all the time though. The main reason for the domination of guitar and piano is economic: you can play more notes at once and therefore have played richer sound with fewer players. You can split the gig money across less people. It really has nothing to do with the number of wind players that can transpose.