Technology has made home theaters commonplace in today's society. Whereas before you needed to go to a movie theater to get a fully immersive cinematic experience, nowadays you can enjoy many of the benefits of a full-fledged theater from the comfort of your own living room. Despite this, however, I would still prefer to see a movie with other people in a cinema.
Firstly, going to a theater to watch movie turns the experience into more of an event. There's a ritual involved-you have to get ready, meet your friends, buy your tickets, pick up some snacks, find your seat, and watch a few trailers before the movie starts. Popping on a movie at home is convenient, but that convenience and lack of ritual makes the movie-watching experience feel like less of an activity and more like a routine way of killing time. I relish the ritual aspects of going to theater almost as much as I enjoy watching the actual movie.
Secondly, by going to a theater, you get to share the movie-watching experience with strangers. This makes watching movies more of a social activity and much more pleasurable. For example, when The Dark Knight came out, I first watched the movie at home with a friend. It was fun, but it was also totally different from the experience I had watching the movie again in a theater. At home, it was just me and my friend reacting to things happening on the screen. Our reactions were predictable, and while we did joke around during the movie, there was nothing too memorable outside of the movie itself. In the theater, though, people were randomly throwing out Batman jokes and wildly cheering during epic scenes. I could tell that these people were big Batman fans, and their passion for the source material made watching the movie much more gratifying.
Finally, watching a movie in a theater is more immersive because of the hardware a theater utilizes. While you approximate the theater experience with a good home entertainment setup, it's difficult to get that feeling full immersion without spending an exorbitant amount of money. To get cinema-level image quality you need a huge TV screen or a really good projector, and in order to mimic the audio of a theater you need a relatively pricy surround sound system. Most people just don't have the resources to put that kind of thing together. Going to a theater allows you to feel your seat shake with every explosion and your body swell with every orchestral arrangement.
All in all, watching movies at home just isn't as fun as watching movies in cinemas. It feels like less of an event, and while you could replicate the sensory experience if you had enough money, in the end you would still be missing the crucial social component that makes theaters so great. For those reasons, I think putting on a movie at home could never replace a trip to the cinema.