I would be for it just to get a benidiction transmog
I did the new campaign that takes you from 1-10 in about 30 minutes, then you are given a quest that takes you to kultiras. Map says you can level from 10-50 there, then its onto the shadowlands (max levels were made to lvl 50)
People are invested in their characters and classic does have a finite lifespan so I could see why people would want an option to do a retail transfer.