The anime medium is more oriented at young adults who prefer action packed, power fantasy stories or comedy. In fact, modern culture has shown a preference for those genres not only in the anime medium. It's really sad that the average person is growing numb towards stories that showcase the emotions that make us human and prefers stories which cater to our primal instincts - lust for power, sexual gratification, violence etc. I feel this is one of the reasons why movies like "The Deer King" are not getting the score and attention they deserve.
The story of "The Deer King" is not very original and does follow a very familiar formula. That, however, plays into the movie's advantage. I will not go into detail why that is the case but I will tell you that you don't need to reinvent the wheel to tell a good story. I don't understand the people who complain that the story of the movie is bad or boring - it's not, it's just focusing more on drama and emotion than on action and lore. It's also extremely easy to follow and the symbolism is there but you don't need to recognize it in order to appreciate the movie.
All in all, this is a production for people who can appreciate good drama and not for people who want fighting scenes, epic battles and power trips. I recommend you watch this anime and ignore the relatively low score that it has.