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.
"It’s definitely something we’ve avoided," Morhaime tells GI. "I think another element, in terms of the gambling question, the question in terms of that is whether or not you’re actually… There’s an element of converting back into real-world value. I think that’s a critical element, and that element does not exist in Overwatch loot crates."
Morhaime adds: "If you’re going to talk about those things, then you have to look at as: 'Well, are people trying to make money doing this?'"
For additional reading, check out Alex Wiltshire's report on the addictive psychology and seductive art of loot boxes.