Th "alure" of the gamble comes from gaining something that matters. Overwatch doesn't really matter, for the lootbox setup, because you already have access to everything that everyone else does. We're all on the same playing field. Cosmetics don't change much.
BF2, on the other hand, gives actual bonuses, characters, enhanced powers, characters and gameplay changes (like playing as a Jedi). These things change the way the game is played, thus, becoming a draw to the individual.
Even ME's MP crates were gambling. Why they didn't get much hate, I don't know, but what ever. Anything that leads to the abolishment of loot boxes has my vote.
Servare's comments