i have been in and around several walking horse barns. there is no doubt that early on in the training of many of these horses,they do make them "sore". it helps to get the horse to tuck his back feet farther under him. once the habit has been made, they don't sore them any more.
with that being said, i think that the walking horse gate is beautiful and for the most part, these horses live much better lives than most horses. the ones you see marching around the field are top caliber horses that live in climate controlled barns and are carried around in semi trailers from show to show. not too bad for a horse. i would love for us to bring them back for every game. i don't think you can have too much pregame pageantry.