This is actually one the major reasons I buy in-store, and as someone who has keen eye, I can say that the quality of paint application for WFC and SS is highly variable. Some paint/tampo jobs (and chipping) are just atrocious, while some are done by a freakin' robot! It's almost a coin toss which you'll get. It's also more fun to see shelves stocked with goodies - all that childhood stuff. So I'm in bind... more paint issues or more standing in the toy aisle like Mr Burns choosing ketchup or catsup.
Did some scouting around the Internet. Legacy Deluxes are also open box and Leaders are closed box. I would think this means Studio Series will eventually follow suit and go plastic window-free for all classes.