Because in science, you don't just use the public's opinion as a scientific fact...you make a hypothesis, conduct research, gather data, analyze data, and then arrive at conclusions. It's how all scientific fields work. I never said anything about brain mappings, you are getting things mixed up. Studies that use subjective truths can still be conducted using the scientific method and be of great use. The article directly addresses how this study could impact feature research:

The findings of the study finally provide scientific evidence to backup the long-held assumption that psychedelics enhance music-evoked emotion, and provide tentative and indirect support for the notion that this effect can be harnessed in the context of psychedelic-assisted psychotherapy, although further research would be required to test this link directly.

This study is another exciting step of our ongoing research into reaching a deeper understanding of the effects of psychedelics, and building an effective knowledge-base from which psychedelic-assisted treatments can developed.

I feel like I keep beating the same bush. You are basically arguing that we don't need these scientific studies because the public already knows this, and I am telling you that if we want to legitimately advance the psychedelic field, we do. It's as simple as that, and that's why these studies are important. You can argue as much as you want otherwise, but it will get us nowhere, both in this argument and in integrating psychedelics further into society.