Games are absolutely art. I don't think there's much room for debate.
Your point about how attached we are 20 minutes into a first play of Last of Us is very poignant. Games can have every bit the drama of the best TV shows or movies, with the added depth of player immersion. It's a powerful combo.
You will be very surprised to see how people suddenly jump up on you when you talk about videogames as art.
It sure is!