The introduction of popcorn may have been one of the first steps of movie theaters to "open up to wider audiences", but as another thread points out, the artificial flavor and smells that surround the product today has not just found friends. Movie theaters, in their fight for customers, have had to lower their standards so drastically to attract new movie goers that others turned away in bewilderment. With the advent of home entertainment technology, both for audio and video, a fair amount of people now prefer the quiet, clean, comfortable, distraction-free screening in their own living room to a night at the movies.
At the same time, we're witnessing a big cultural landmark of the 20th century is dying out. It already has in some forms that had to make space for the mega multiplexes and super blockbusters.
In this context, the introduction of popcorn may have marked the beginning of a development in which the original attraction, the movie, became just one factor among many in the "movie going experience", thereby being devalued. In the end, movie theaters will have to answer to the question why they expect their customers to pay premium prices for these factors.
The business model of movie theaters, with or without popcorn, is not sustainable any more. Whether the disappearance of the cultural entity "movie theater" in its present form would still constitute a big cultural loss, or whether that loss has already happened long ago, is certainly worth debating.