They are what they are. The same thing happens with Cage's and Feldman's and Wolff's music. There is nothing to hear but the sounds themselves. There is no development, no predictability, no beginning, no end. There is no introduction and no finale.
Nothing is expressed.
The pieces are not there to provide a virtuoso performer with an opportunity to shine. Happy New Ears. Their music speaks of nothing. But this nothing is not nothing, it is rich. Feldman, on the other hand, was more sparing in his writings and has a more cryptic style, often spiced with anecdotes like some Zen teacher dropping koans.