In my view, no state has a right to exist in and of itself; they ought to exist conditionally based on the collective will of their inhabitants, and the absence of oppression. A state that oppresses people - especially one that oppresses people based on their religion, ethnicity, race, sexuality etc. - has no right to exist in my eyes.
EDIT: For the record, I believe the original UN plan would have been unworkable from the start - which is why it blew up almost immediately upon contact with reality. I don't think it would have caused any less misery than the ethnic cleansings of the 1948 War, if followed to the letter.