Because it's very likely to be recognized by the UN, which will force the negotiations to focus on the issue of borders and accomodating exchanges of territory. It's the only way to successfully pressure Israel into getting serious about negotiating THAT core issue, upon which agreement on all other details and incidentals can then be based. Otherwise, Israel is destined to play the game indefinitely, while it whittles away at the West Bank.
White House: TPP deal will pressure China to raise labor standards (Reuters)
from the article: Arab League may bring settlement freeze debate to UN