Here's the rub. Your epistemology is something along the lines of (I apologise if I get this wrong) "we can know things when there is sufficient scientific evidence for them". But how do you know "we can know things when there is sufficient scientific evidence for them"? Maybe you claim it's because using this knowledge we can build rocket ships (amongst many other extraordinary accomplishments); but why should building rocket ships be taken as evidence for any sort of knowledge; alternatively, maybe the rocket ship is an illusion? Eventually, if you go far enough down this epistemological rabbit hole, you will find that the only possible answer to these questions is some variation of "common sense".
You are right that we can use this to justify most anything, but we can use most anything to justify most anything. We must tread carefully, and, most importantly, rationally, but not treading at all is a poor choice.
When I walk into a wall (as one does), I feel it hit me. When others walk into walls, they describe very similar sensations and observations. We can come up with explanations for why we should all feel running into a wall. You could explain this by saying all our subjective perceptions coincide, but there is no actual wall in any rational sense; there is nothing provably wrong with this explanation. Similarly, when I perceive art I find profound, read what other's perceive in art as profound, and look at commonalities in profundity in art across cultures, I could conclude that there is nothing too this profundity in art thing beyond a coinciding of subjective perceptions; there is nothing provably wrong with this explanation. However, there is a wall, and there is, as far as I can tell, characteristics of artworks that make them profound.