Why not? It's what everyone else does. What is fun and entertaining depends on the individual. That is, it exists only in their head.
Entertainment can be many things, and "simple laughs" is one of them. An entertainment product that succeeds in providing mindless fun is better than one that tries and fails to offer something more.
The rest of your post can be summed up as: Hey man, like, open your mind. You'll, like, totally learn and appreciate stuff.
Yes, that does seem to the problem with this particular discussion. If I press 1 on the keyboard and then aim and press the mouse button to shoot the enemy, then I'm interacting with the game world. You seem to be asking for a choose-your-own-adventure style branching storyline.
Lack of branching story lines isn't really a new problem (as in games being so expensive to make now) as the more branches you have, the move work the developer needs to do, which is as true for both AAA blockbuster RPGs as it is for text adventures, and not every developer sees it as a valuable thing. Valve, for example, makes strictly linear games as they see no value in putting extra work into something most people won't even see.
I prefer games like Deus Ex, Thief, or Hitman which feature mostly or completely linear stories, but allow me a bit of freedom in how I complete missions. Freedom in how I interact with the gameworld in order to advance the story, even if the story itself remains the same. The end slides of games like Fallout and Dragon Age are nice, but I prefer small changes that occur while I play, rather than big changes that I can read about once I've finished playing.