A movie designed to do well on a RT score needs to please everyone. The end result is something that tries to be bland, uninteresting, and inoffensive. As an avid movie goer, that is a horrible result. I would much rather see a movie that takes risks and fails than something with little ambition outside turning a profit.
If you ask people why they don't go to the movies more they will often cite the idea that there is nothing new they haven't seen before (besides the complaints you hear about prices). That is another way of phrasing this exact problem. It is becoming more and more risky to innovate and try something new. You end up with lots of sequels, remakes, and other cookie cutter projects. It is safer to invest in the next mediocre superhero movie that most people will be fine with than an innovative middle budget drama that might have a harder time finding an audience. That is what is hurting the movie industry.