Online multiplayer - I like the idea of it, but can't really will myself to get good enough at a game to be at a competitive level (if I'm playing online multi, it's just casual and for fun). Local multiplayer is much more rewarding for me.
Crafting - it was novel in the Star Ocean series, but nowadays it feels that even non-RPGs are shoehorning this in. Even more frustrating is when you are playing a game, discover a treasure in a tricky dungeon, and it's nothing but a new crafting recipe... what a way to deflate the excitement of finding a new treasure! Crafting also feels like a way to artificially increase grinding, now instead of grinding gold to buy items (which, at least you know how long this'll take you - if every enemy drops 10 gold, and a fight takes ~5 minutes, and you need 100 gold... then you'll have things in ~50 min), you have to just hope the drops you need come up.
Minecraft - I've never played this but I really liked DQ Builders, so *shrug*. Steve in Smash had me going 'meh'.
MOBAs - every video I've seen of one and I have no clue whatsoever what is going on... they seem to be a UI nightmare with a shit ton of particle effects.
Inflated game lengths - look, I have nothing against long games (my favorite game this gen is Cold Steel III which took me close to 130 hours to beat, and I play tons of long-ass RPGs), but too many games feature lots of padding that could be trimmed and be none the worse for it. Sometimes, I don't mind a game that's quick to get going, that you don't need to sit down and devote a few hours at a time just to make any kind of progress in it. But so many people feel that long-ass game time is a selling point.
Roblox - I thought this was Minecraft with legos, but it actually sounds kinda cool now that I look into it more? I bet if this was around back when I was young I would've gone apeshit over it.
Streaming is one of the few "today's gaming culture" things I do get - although with me it's watching speedruns of classic games, or fighting game tourneys.
I also see a lot of people not into Youtube... but there are some fantastic deep dive channels for gaming (of course, my preference leans toward retro and the obscure):
Chrontendo, Generation 16, Game Sack, Kim Justice, SegaLordX, Top Hat Gaming Man