How are they being "tricked"? No one is secretly siphoning money from them. They are for the most part consenting adults who have free will.
It's problematic. It makes players feel bad, in retrospect, when they realize that they've spent more than they would have wanted to spend at the outset.
I would hate for the loot box model to move beyond video games. Can you imagine going to the store and having to buy a mystery box filled with groceries, which you may or may not need or want? Gosh that would be horrible. Not that it would happen but, still. I feel like we should encourage a society with clear prices on specific, concrete products. I give you $10, you promise me specific thing X. If I don't actually get X I can ask for a refund, or I can sue you even if it turns out you're acting in bad faith, etc. Loot box systems don't seem to transact in good faith.
The loot box model is video game adaptation of the collectible card game model which is itself a gaming adaptation of the (non-gaming) trading card model, both of which predecessors have other non-video-gaming derivatives, so the basic model is already lots of places besides video games.
Its already there, targeted at kids! Its all the collectible toys in food such as chips.
Wuppies, flippos, "voetbalplaatjes" [1], are just a few local examples.
McDonalds Happy Meal toys must be a world-wide example?
The lottery is legal and government run in many (most?) states. We already live in a society where people willingly give their money to get something.
Also the X gold coins for $X is less of a problem. The old League of Legends style of a "free to play" game was great. They were one of the first to do it. You paid money for a currency, and then the currency purchased items. All items had an alternative cost as well for a currency you could only earn in game. It was explicit about what you were buying.
Loot box systems on the other hand are not explicit. Blizzard's Hearthstone for example, as I talked about in this post https://news.ycombinator.com/item?id=15983166