Teams with more than 2 colors have more options. In addition to standard white and gray, Boise sells blue and orange gear. You can get the exact same shirt in 3 different colors. At BYU, that's 3 colors white, gray, navy. Potentially 25% more sales right there with just an extra color....for BYU it should be royal blue--you'll notice no royal blue stretch Y gear currently.
Also, BYU has not legit mascot gear as I noted above. Mizzou can sell Tiger gear, Georgia-Bulldog, ASU-Sparky, fork logo, Carolina-Tar Heel. BYU mainly only has stretch Y gear and "BYU" gear.....no real cougar mascot logo. You may not like it or need it, but others do and will buy it.
That is it...more colors and a more marketable mascot logo.