http://www.pcgamer.com/blizzard-president-on-loot-boxes-i-dont-think-overwatch-belongs-in-that-controversy/

According to the ESRB (Entertainment Software Rating Board) loot boxes are not gambling—despite the surrounding and ongoing controversy tied to randomised item systems. Speaking to their inclusion in Overwatch, Blizzard co-founder and president Mike Morhaime feels the shooter's interpretation of loot boxes is fair game. 

In conversation with GameInformer at Blizzcon 2017, Morhaime suggested there is "absolutely nothing wrong" with crates that offer randomised items, and that "whatever the controversy is" he doesn't think Overwatch deserves to be named in the overarching discourse.