As long as the contents of the boxes are purely cosmetic and have no ill effect on the mechanics of the game, more power to them. If their cosmetic change has any adverse effects on the performance of gameplay of other players, that poses a small hidden problem.
An example would be that a cape or whatever could be a woodland camouflage pattern and would making hiding near trees and shrubbery a very sought after effect. Messing with people's heads with the use of cosmetic items is still Pay 2 Win.
I could also be completely psychotic and wrong on several levels.