A recent story that has brought into question series endings as well as artistic vision has been the whole Bioware/Mass Effect 3 ending that has managed to go from an industry specific topic to national news and even spurred Forbes to begin analyzing the industry. This is really interesting because it is an argument of artistic expression versus respect for the property for fans.
The primary dispute that critics are using to defend the flawed story of Mass Effect 3 and often what many writers also rely on it the idea that it is art. The story is an art and the creator has full artistic license to craft the work however they see fit but this isn't entirely true.
"Many definitions of art have been proposed by philosophers and others who have characterized art in terms of mimesis, expression, communication of emotion, or other values. During the Romantic period, art came to be seen as "a special faculty of the human mind to be classified with religion and science"-Wiki
When an artist creates their piece of work it is what they envisioned and they are ultimately only constricted by how they perceive their own work. This entire process changes when the artist chooses to share their work with others as a career. The work then needs to become commercially viable.
In every artistic medium there are criteria that need to be addressed for the work to be accepted by enough critics and individuals to be a viable work.
What this means in short, a toddler's crayon drawing may be art to their mother but no one is likely to be buying it for thousands of dollars. In writing terms if someone writes a 200,000 word novel with the grammar of an eight-year-old and refuses to address these issues no one will publish it or want to read it.
For all of the artistic intent every work needs an outlet to be viable. In the writing industry, as in photography and film these are publishers. Publishers set criteria for all works because they have a set target market and prospects for those works already that also establish the work's commercial viability. It's an assurance that any work that they accept will be viable for them. If the artist's work does not meet their criteria then it will not be accepted or they will request it is changed to suit their criteria.
When I was editing Nightfall for my publisher their requirements were fairly simple, no profanity and no trademarks. I had no problem dropping the cursing, it opened up the audience for my work but I found more difficulty with trademarks, mostly giving up car models. In the end it was just a matter of edits.
No matter the medium, if an artist wishes their work to be successful then it should be expected there will be changes that need to be met. If the artist resists the recommendations, then they should also expect the criticisms that come with that choice. While the work may be a piece of art it is also a product. If the customers are not happy with the product while the artist defends their work as art then they should know that they will have fewer customers next time.
While we regard writing as an art form, artistic expression in the finest, we should always be wary of claiming it's our artistic license to make certain choices about our work. If we want to succeed as authors we need to accept the criticisms and make the changes that make our works viable, otherwise it's not a career in writing just more unpublished works in our desk.