Well, your analogy is even more flawed. I hardly think a painting store is going to be OK with you treating their stock like you own it. Also, once they sell a painting, it's gone and you no longer have access to it. Just how exactly do you propose an artist make an income if their output should be free for all to peruse as they see fit? Exposure doesn't put food on the table.

Not that I am in any way defending the fine art business which is nothing more than a giant money laundering scheme for the filthy rich.