Different strokes for different folks. I love Rothko, but I don't love every other famous modern artist. (Twombly in my opinion is filthy childish grafitti, for instance, and Rauschenberg does nothing for me.)
I agree about Twombly and Rauschenberg. I know what we are "supposed" to see and say about their work, but it still does not go to a deeper level. Over time, the important artists will be seen for their deeper content. Then people will tire of those works and seek others and resurrect their reputations from the dustbin of history. But the shallow artists will sink. Rauschenberg, and Johns, were clever. Perhaps Johns cleverer than Rauschenberg. But pasting things together from everyday life, with no deeper retrospection, doesn't work for me in the long run.
Rauchenberg's Monogram; Johns The Critic Sees (look carefully at that one: glasses and two mouths, not eyes) and Twombly.
I hesitate to post the Twombly, because I know how Freepers will explode on that one. If you search for images of Twombly, you will see variety in his "scribbles." But I sometimes think the luckiest artists are those who latch onto a major style with a subtle variation, so they can get attention without having to make major creative breakthroughs and all the work (and frustration) associated with that. But I also think that in the long run their art is less likely to be respected.