Unfortunately most single player games have devolved into this. It's hard and risky to develop novel gameplay rather than just building an interactive movie around tried-and-true game mechanics (run & gun). Most gamers are ok with this, just like most moviegoers are ok with franchise films (sequels/reboots/remakes).

Media are just converging toward low-risk, formulaic, and consistently profitable goods. It happens at a speed inversely proportional with the complexity of the medium: music has been manufactured for a while, more recently movies, now games. Novels have proven trickier thus far. Readers seem to appreciate originality more and are more discerning, with a lot of surprise hits (and failures). It's only a matter of time before that formula is cracked though.

You couldn't be more wrong. The GTA titles are great sandbox games.

I think you hit the nail on the head. Being able to choose your own adventure has been captivating even without the visuals. Zork was captivating using ASCII, this even more so.