I watched a video of a pianist performing 4' 33", and someone in the audience coughed, and someone shushed him.
I think there are many profound things to say about silence (or many profound things to meditate on, if you prefer), but in the end, 4' 33" never rises above performance art. There are ways to draw an audience through silence into a participation with an artist, but that participation has to be externally focused. The audience members have to be allowed to step outside themselves. A work that places the focus squarely on the viewer's reaction to the work, so that the person watching is also constantly monitoring his or her watching, is no more art than a mirror is.
And silence without any external focus is a nothingness. All art is a shaping, a definition. Music is shaped sound. Acting is shaped reality. Silence only bears fruit when it is a shaping of thought and soul. Otherwise it's just a vacuum: the tyranny of ambient noise. Which is really not all that far off from Cage's intention: "They missed the point. There's no such thing as silence. What they thought was silence, because they didn’t know how to listen, was full of accidental sounds. You could hear the wind stirring outside during the first movement. During the second, raindrops began pattering the roof, and during the third the people themselves made all kinds of interesting sounds as they talked or walked out."
And yet created things seem only to yield their beauty in peripheral vision. C.S. Lewis says in The Four Loves (this is from memory) how counterproductive it is to go into a garden specifically to look at its loveliness, because so many grubby bits of reality keep getting in your way. But go into a garden to say your prayers, steadfastly refusing to be distracted by the delights of the garden, and nine times out of ten you come away refreshed with a idea of loveliness that direct contemplation could not reveal. The true beauty reveals itself not in the direct sensual experience, but in the distillation of reality that comes when the physical world is made subject to the spiritual. The first reading the other day -- the bronze serpent on a pole, made by Moses, which cured the people of the bites of snakes -- was another example of this idea. The image is somehow stronger than the actual serpent. The image of the serpent can undo the destructive power of the real serpent. Gregory of Nyssa uses this example as a foreshadowing of Jesus, not just in the thing being raised up curing the people, but as the power of the image being stronger than reality. On the cross, Jesus was the image of sin without bearing any actual sin. By bearing death, which is the ultimate manifestation of sin, without bearing any of the content of death, he made death implode on itself.
By contrast, 4' 33" is the reality of silence without the idea that produces silence. And that's boredom, pretty much.