My reasons...
#1 - They stink
#2 - After a few months mice are too small and multiple prey items are required at each feeding
I usually try rat pups first, but have no problem offering hopper mice to get them going. I usually only do that for a month or so to get their feeding response going...after that it's back to rat pups. If they don't take the rat pups, it's back to hopper mice for a few meals and back to rat pups again. They usually give in...eventually...
And I agree about the nutrition content...the difference is negligible imo...although the internet says otherwise...I think rats are just more convenient for most people...