It's common for people to think that art is completely subjective however i argue that isn't the case. Art has some degree of objectivity to it based on certain principles.
People who understand art, understand that there are various techniques, skills, criteria, philosophies, and concepts involved in artwork. Movies, music, T.V shows, paintings, drawings, and so forth are all examples of art forms requiring technical handiwork. Forms of art such as movies, games, shows, etc. have a certain level of skills involving several things:
1) Story writing - This has a general format of a beginning, middle, and end. There are also conflicts, character, and plot development. There can be a struggle between good and evil. There are also other literary devices such as foreshadowing and changes of direction like plot twists.
2) Visual arts - This can range from digital painting, CGI, designs, and so forth. This may require knowledge of computer programming and other sophisticated tools to achieve.
3) Story-telling - Voice acting or acting and methods of story-telling through cameras or other means are examples.
That being said, there is a difference to measure bad art from good art. If i suddenly made an amateur movie, the quality would be no where near popular films like "Lord of The Rings." This is because i lack expertise in Screen-writing, story-writing, direction, visual arts, and other things that Peter Jackson has. Directors like J.J Abrams and actors like Jodie Foster have technical skills that require professionalism. Whether or not you enjoy it is subjective but the work's quality is measurable.
There is a general criteria for judging good and bad art:
1) Originality - Is the artist's work cliche or is it a uniquely distinguishable piece? Elements from culture, values, genres, and so on set parameters on what is "original." For example, i find artists like Marilyn Manson original. This is because his fashion of dress, gimmicks, and artwork deviate from the norm. Cliche ought to be frowned on because it does not progress art nor generate new ideas. New ideas cannot therefore breed new styles of art.
2) Creativity - What artistic expressions create something revolutionary and of value? This can be measured by culture, values, and compared with other works. Creativity depends on how well the artist understands the type of work he is involved in. It's by this that we have a framework to determine whether or not he's being creative.
3) Quality - The quality of resources available to the artist depends on what type of art they are doing. Some art forms like poetry do not require as much resources as game designing. The more tools you use, the higher expectations to judge your work's quality will be.
While there's no way to distinguish objectively between who's a "better" artist, there is a way to judge whether or not a person has reached their uttermost potential. This is the goal of constructive criticism and it's vital for improvement. There is a difference between a valid and an invalid opinion. A well informed critic who has studied various subjects surrounding art is qualified to make an expert opinion vs. someone who says "this is rubbish!"
People dislike constructive criticism because they'd rather believe that their art is perfect. You as an artist can ditch constructive criticism but there will be consequences. You probably won't get the fame or respect that you want. Essentially, you won't grow as an artist. While there may be some contests that are biased, others evaluate your work.
What about mainstream artists like Justin Bieber who achieved fame and fortune? In my opinion, they accomplished that because they had other things to substitute for their art. Connections, record labels, popularity, fashion, beliefs, and many things make them appealing. I dislike artists like Bieber because he's not as passionate about art as he is being a celebrity. His music is generic and nothing special. I'm not arguing that every mainstream artist does this. There are exceptions but they'll most likely be recognized for their ingenious work by artists looking for high quality content.
Claiming that we should appreciate art for it's own sake assumes that all artists do this which isn't always true. Corrupt people have used religion, science, ignorance, and many other things to gain profits. Art unfortunately is a way for corrupt businesses to make money. Very reputable modern artists have made millions from their masterpieces only to become too self absorbed leading to their work's downfall. That's why it's not advisable to buy just any person's work. Consider that the money you invest in low quality work may satisfy a company's greed while the underrated artist with a strong work ethic gets little to compensation. By refusing to buy anyone's work even from your favorite artists, you are disciplining them to strive for their potential. You are truly supporting them by teaching them that it's all or nothing. Many artists who are very passionate about their work go to extreme lengths to complete it. Some even put their health and lives at risk to express their art and entertain you. If everyone followed these principles, we would live in a world where hard work brings success. We would live in a world where everyone can get what they bargained for. Sadly, this isn't the case thanks to money, fame, bias, society, and many other things.
There are different reasons based on different experiences for why people enjoy art. Our emotional reactions can be subjective but art is not compromised of just feelings. I may not be inspired by most of Eminem's lyrics, but i won't deny that he has a developed a complex flow. The intellectual aspect of art still exists and it begins with observation. We can choose to hold fast to the belief that art is subjective but we will never go beyond the simple phrase "I like this just because.." By choosing to act only upon impulse, we will never understand a deeper meaning of art theory. This doesn't mean you should go to an Museum to appreciate art. You can still enjoy whatever forms of art you like. I simply advocate for opening your mind to new perspectives, constructive criticism, and artistic disciplines. The beauty of art is that it invokes subjective sensations from objective craftsmanship.