The only “only on iPhone 15” titles I can think of are Death Stranding, RE4, and RE Village. There are a number of games that play better on iPhone 15 (Honkai Star Rail, Genshin Impact, Warframe, Ex Astrid) and some that have special version/assets for the latest hardware (CoD Warzone). Part of the fun of new hardware is seeing how an old favorite plays .
Not a dramatic difference, but significant. For example, you can play Genshin Impact maxed out at 120FPS.
Fair enough, I never thought I would say this, but the USB C will equally be a god send. I think it’s time for lightning to go.
I did like lightning, but it is the convenience you talk of. I take MagSafe these days, but it would be handy if I could lose that too.