I don't believe that HT is killing the theater experience. Even a 10 foot screen can't match a really nice theater experience.
I think Theater Chains are killing the experience.
In College we had a guy on our dorm floor who was an Assistant Manager for the local Regal Superplex. His stories were absolutely frightening to me. It totally changed my view of the industry.
When I was a kid there were these scary people called "Ushers," and they had a flash light and you didn't want to be the kid caught in that beam. Getting kicked out of a movie was the worst. So you behaved because you were scared.
Today the Multiplexes are run out of fear. Instead of Ushers, they have HS kids who tear off your ticket and poorly help clean the theater after the film plays. The managers have to really be enticed to even try and quiet someone. They are scared of the bad attendees.
Just about half of the people they kick out or make a scene in front of end up calling the chain and complaining about them. That complaint goes on their record and ends up ruining their chances of a bonus. The times that the kid on our floor would tell us about him getting reemed for doing the right thing (kicking bad kids out) was to me very disheartening.
On the other hand...
There are some privately run theaters in Texas that are extremely popular. One chain the Alamo Drafthouse is somewhat famous and it's for more than the beer you buy there. They actually police their showings. Every film is started with a trailer that pretty much tells you to shut up or they will take your ____ out. I could only find a few of the trailers online but they're humorous:
There is a privately owned theater near me that is extremely nice. Leg room for people around 6'6. Great sound and great picture. Plus the owner is generally there and he will kick you out for talking. I saw a movie there this past summer where he stopped the film, came in kicked the people out (about 9 people) and then restarted the movie. He apoligized to everyone and said he would have something for us after.
He was waiting for everyone when we exited with free raincheck passes that he said could be used anytime for any movie. He also handed us $5 Gift Cards that could be used at the concession.
So there are still some shining lights out there doing it right. I still prefer IMAX over any other way of seeing a film. The last Harry Potter was really good there as was Beowulf.