Israelis are shrewd negotiators and know exactly how far America is ready to go with its pressure on Israel. You don't deny there is pressure to negotiate, do you? And that American demands are beyond what Israel is ready to do. Now, are you asking me whether American demands are reasonable, and why would America want to pressure Israel to accept American demands?
As to your yet another question, since I do bother to respond on point, the answer is maybe I don't know. I doubt the US will ever push Israel much beyond what Barak offered, and Arafat rejected that flat out. So the bottom line is that even if Israel did exactly what the US wanted it to do, when it wanted it to do it, there still wouldn't be a deal. Get used to it.