It gets good reviews because it’s fun to play. The game is good at its core: you have to scan machines, aim at weak spots, move a lot in the battle to avoid damage, choose right weapons, or you can override a machine and enjoy the show, there are so many options and challenges. Besides, let’s not underestimate the value of good graphics. They make the world nicer, more enjoyable, make you want to come back and play again. I understand that this game is not for everyone though.
I wouldn’t say that Horizon aims to be super realistic. I mean, it’s not far away, especially if we compare it to Elden Ring. But in Horizon colors are saturated, the game looks too beautiful and vibrant to be realistic in my books. I would say Hogwarts Legacy is a better example of a too realistic game: colors are bleak, objects and textures are much closer to what we can find in real life, it does look generic as you say (at least IMO).