File: 1429428038561.jpg (103.71 KB, 852x937, Beret - If I can't tell what i…)
The definition explicitly states that art is a creative expression that is to be appreciated for its beauty or emotional power; it is not saying that it needs to have a quantifiable level of these things. Pop music is as much art as classical. The only real difference is in which social groups consider them worthy of their time; the social standing of the art and artist in their or others' environment.
I.e someone making music exclusively with bathroom appliances might be hailed as 'daring' and 'satirical' by one group of critics, while another think he's being a tosser.
Regardless of opinion it remains art, the qualities of it being art is subjective; not its genre.
If you want an actual art debate you can pose the question: "Is a commercial creation, such as a big Hollywood action movie created on a pre-existing brand, art just as much as a creation that is not motivated by financial gain?"
Because on one hand that means 'Django Unchained' (2012) is art, but 'The Theory of Everything' (2014) is not. Debateable but a premise. On the other hand 'Star Wars: A New Hope' is art, but 'Star Wars: The Empire Strikes Back' and 'Star Wars: Return Of The Jedi' are not.
At least that's a debate with merit to it.
TL;DR- Your opinion of an art piece does not dictate its status as art.
Also saying we "don't know what art is" is fucking dumb; read a book.