Gaming

I'm mostly a single player person, like 90% of the time, so I feel like I don't have a dog in this (I can't say "games aren't fun anymore", because all I need to do is look at Steam to prove myself wrong; I'll find some weird or fun looking indie or AA games in that sea). That being said, I think I know what you mean when you say "structured" fun:

Instead of being left to play the game your way, learn it, master it, even break it by finding some glitch or exploit (which normally get fixed in the name of balance. Understandable, but sometimes having overpowered and unbalanced things ingame makes stuff even more fun), there's a "path" the game clearly wants you to take to succeed (usually meta gear), stuff like "headshot 5 enemies with X gun in 5 seconds" or "kill an enemy player while rocket jumping" are now achievements for you to earn rather than stuff you'd do of your own skill and free will (maybe not the right words for that, but it's what came to mind lol), and like another comment said, the devs are now trying to monotize every move you make, instilling FOMO, and trying to get you to buy boosts so you don't have to do the intentionally harsh grind for the stuff and other advantages to tip the odds in your favor.

....Or I could be completely off base with that second paragraph and you meant something else when you said "structured fun"