The Ring of Honor is a given. The question is whether Dak deserves recognition beyond what any other football player has received. The cool thing about retiring the number is the school can continue to sell "15" jerseys for years without worry about being accused of trading on a current player's likeness.
I don't know about State, but I know for UGA this year you can only buy jerseys with the numbers 1 (for "We're No. 1!"), 15 (for the current calendar year) or 34 (for Herschel, who's number was retired).