Most people do not understand the skill or craft required in aspects of art and music. They do not appreciate it. They may enjoy it in general but cannot appreciate the technical aspects without the background or education. For example, they may enjoy bold colors without realizing the colors come straight from the tube and the artist did no real work in selecting those colors or they may not appreciate the order and precision of brush strokes to achieve certain mark making shapes.
I think you're gonna need to unpack how you define "most important" and "critical" here.
It's quite easy to see most people enjoying a lot of art and music (I personally wouldn't include much 'understand' in my own definition of 'appreciate' here).
The more you study something the more you can have nuances or less-widespread angles by which to appreciate it, that will lead you to appreciate different things, but that's not the same as requiring that study to appreciate it.
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From another angle: critics have claimed that the Beatles were less important than various less-popular or more-niche musicians of their era since the 60s (from many different angles, even then). Is there a point where sustained higher popularity negates that criticism? Does time overwhelm niche more-highly-trained criticism at some point?