The faster the customers eat, the faster there's a new seat available. Many restaurants have a standard set "table time" that they want each customer to spend in the restaurant. You may vote with your wallet, but many, many more would need to join you. Even a 10 minute reduction in time spent per customer at a restaurant can make them oodles more cash.
These tactics are intentional, and meant to help keep customers moving in, eating, and moving out. All this "enjoy the ambiance" stuff is great, as long as it doesn't get in the way of getting more customers per hour. I used to work at a Red Robin, and though the food was amazing, especially for the price (I can taste it in my mind as I write this), they were one of the worst offenders in the sound department, even in the kitchens.