It’s because it’s a feature 0 people will complain about adding if it all works well. It’s a small, minor, completely unnecessary detail.

If it’s there, then someone had the time, the energy, and the freedom to add it, just because they wanted to. It’s not an item that will make it on the checklist of a minimum viable game.

If it’s there, it’s a very good sign.

When you see a dog you want to pet it. It’s nice when they place that little extra detail.

Because people like dogs. And like to pet them, even virtually.

I’m thinking because it’s as nice as it’s pointless, thereby showing that the devs were detail-oriented in how to delight players.

To add to the other responses, I think there’s maybe a sense of relief or novelty in it, as the rest of many of these games are intense and/or violent. Having a little wholesome moment in the midst of all that really stands out.

Maybe because of this: https://en.wikipedia.org/wiki/Can_You_Pet_the_Dog%3F

My wife and I spent an unreasonable amount of time petting cats in Hogwarts Legacy.

Unless, like in Hogwards Legacy, it is an unskippable cutscene when you pet a cat…and these guys are in full stealth mode most of the time so when I try to open a box but end up stuck in a catpetting animation for the 100th time…senseless rage over a video game