Because you cannot reverse history. American has taken the land of the indians, Romans then Arabes has conquered the land of Israel which had belonged to the Israelites, Now the Jews are back to the land of Israel and are ready to share the land with the palestinians. Hamas does not even accept to share the land, Gaza was given back to them and see what id happening they fire at Israel, How can Israel trust that peace with Pals will bring calm and not a disaster on them.
U.S. State Dept. condemns 'vicious terrorist attack' that killed Palestinian infant (Haaretz)
from the article: Preparing for Israel's previous war, not its next peace