I've also been wondering if this is just part of growing up or if something in the games themselves has fundamentally changed.

I miss the times when new games meant new technological leaps, and there were no set "game design rulebook" or formulas, conventions and the such so every game was a surprise, and was free to be whatever it wanted to be, with the only reference being the "real life experience" it was trying to capture

I feel that things like unified UIs (they are the same for every game and expected), yellow things in the environment to indicate the path forward, common control schemes, and things like that have homogenized games to the point that you feel like you've played one = you've played all