There's a spectrum of activity.
CS:GO skins lie at one extreme. If you pay $2.49 to open a case and win a valuable skin, you can directly sell it for cash on the Steam community market, with Valve pocketing a cut of the transaction. Skins have also become a form of currency used in casino and sportsbook gambling.
You can buy skins for real money on the Steam community market, gamble them on a game of roulette on a site with Steam API integration, then cash out your winnings on the community market. Valve's role in the process is absolutely brazen.
The situation with FIFA Ultimate Team is slightly more murky - you can't directly cash out cards or coins, but the in-game trading mechanic effectively facilitates transactions in real money. You can open packs, sell the cards for FIFA coins, then trade your coins for cash through a third-party site. In-game items are used as tokens in third-party gambling activities. Unlike CS:GO, this third-party activity isn't facilitated by an API provided by EA.
This is vaguely reminiscent of the loophole used by pachinko parlours - you can only convert your pachinko balls for non-cash prizes, but a vendor just around the corner will give you cash for those prizes.
FIFA-related gambling has led to criminal prosecutions in the UK.
http://www.gamblingcommission.gov.uk/news-action-and-statist...
Overwatch skins can only be won from lootboxes and can't be traded in any way, so Blizzard probably have the strongest claim to legitimacy. Opening Overwatch lootboxes might mimic gambling in some respects, but the "prizes" unarguably have no cash value. The business model strikes me as a bit seedy, but it isn't obviously within the purview of a gambling regulator. There may be a case for regulation under consumer protection laws, but it's not obviously different to baseball cards or blind bags.