It could obviously be argued that a play is an end unto itself. That the purest way to experience a play is to sit with it, watch it, think about it, and leave it at that.
But that, thankfully, is not the way human beings have constructed their world, and not the way in which most of us process anything. In fact, art is in conversation with the world, and the world should be in conversation with art. When we get together for drinks after seeing a play and talk about its merits, we're all playing roles. Some are reviewers ("I really enjoyed that!") some are critics ("I feel like this really sticks out in this artists body of work because it touches on familiar themes...") some float in-between.
In my mind, the news media captures this spirit and puts it into a larger context. That's why I actually am very happy to see many different responses to a work. Those responses don't have to destroy or create one's own opinion, but they can augment the reason the show exists at all. We're creating work in order to inspire not only gut level responses, but complex ones, and everything in between.