Copyright and intellectual property exist because we've decided as a society that we want people to spend serious time and energy making these worthwhile things. Absent protections, the upfront investment of time and effort aren't worth it. If one cannot control the use of one's original works, only the wealthy can afford to chase that sense of accomplishment.
I am an author who is able to earn a modest income from my body of work, but only because I have spent almost 20 years creating a diverse collection of writings, and copyright law mostly protects me from having to compete with other people selling my writings. I say "mostly" because I find my work plagiarized once in a while (often with the word-for-word copies of my work earning more money for the plagiarizers than it does for me).
On a surface level, I understand the critics of intellectual property. I concede that all art is derivative to some degree, and nothing springs from a vacuum. I acknowledge that even greater art can be achieved if something can be iterated upon by a diversity of artists. But the harsh reality is that most of the people who want to repurpose art aren't doing it to create something new and distinct, they just want to profit from hard work without doing any themselves.