mmm .... I don't agree with that. A great many people have seen Tracy Emins unmade grotty bed - but aren't in the least touched by it.
Any subject studied to a high degree is no longer totally accessible to the world at large. I don't understand rocket science but can appreciate that there was a heck of a lot of very clever stuff going on to get the probe to Mars etc and enjoy seeing the images.
Similarly art is appreciated at different levels by different people, the more you study it the more you get out of it - just like any other subject, science or art.
Art that may not be widely known, and even if it is may not be appreciated by the general public, nevertheless has knock on effects. One example is Op Art in the '60's - it influenced Mary Quant (fashion designer for those too young to know

) and people were wearing dresses influenced by the work
Work that is popular with the public in its day may not stand the test of time.
Today there is a lot of dumming down

but the stuff that is shallow - Keith Haring, whatisname with his sickly cottages - Kincaid - will disappear as passing fads of no worth. Time filters out the best.
Gwen John wasn't widely appreciated in her day, whereas her brother Auugstus was highly successful. With time, she has become the more respected artist (as her brother forecast),
Music, Theatre, Literature and Art will always have degrees of intellectual accessibility - not everyone will read Dickens or Vikram Seth or go to see good contemporary art or be affected by it except indirectly.