Many people enjoy the experience to go out, have dinner or drinks, go to a local (independent) movie theater, interact with the people that work there, sit and hold hands with your SO, eat popcorn and watch a nice movie without being interrupted by anyone, without looking at your phone. Honestly, most of the time I don't even care what movie they're showing.
Obviously YMMV but that's what it's like for me.
One of my primary preferences for watching movies in a theater is my engagement while watching. When I'm at home, I can too easily become distracted. Setting aside time in my schedule and being in a different environment helps me to focus and appreciate more details.
Also, if you're in a metropolitan area with access to an art-house theater, the types of films shown is often far more eclectic than current blockbusters. They can include showing of rare 35mm/70mm prints, short films from movie festivals, foreign films that tend to get limited releases in the US, re-releases of older classics. There's a lot of content that can be very difficult, even impossible, to find on streaming services. Those types of cinemas also tend to have much more respectful audiences, making the experience enjoyable to everyone there.
One of my local theaters offers film classes which entails showing a series of films, once per week, with group discussions held after the showing. Finding other movie aficionados and getting to engage in discourse is a great way of getting more from a movie watching experience. Not everyone has social groups which want to watch films in the same way. Many of my friends are happy to hang out and watch the latest Marvel release, but generally have no interest in watching anything released from the 70s or earlier.
It's also a (relatively) cheap and low friction option for a date, going out with friends, etc.
I honestly did wonder if the pandemic would permanently shift movie theater going as a behavior but the box office results suggest not--and that's with things not yet back to normal in much of the US.