I do, because two injustices do not a justice make. One may disagree on whether creating Israel was an appropriate thing to do (I, personally, believe it was not), but by now there are some 5 million or more people for whom this is the only conceivable home. At this point, I think, Israel is a fact, and its existence does not need any justification beyond the one needed by any other nation state: it is there, and getting rid of it would be a personal disaster for many.
At the same time, I firmly reject the idea of Israel as a Jewish state that has anything to do w/ myself. Israel is an Israeli state, the state of the Israeli people, which, in my view, has little, if anything, to do w/ those of us in the diaspora. I have no loyalty to it whatsoever, and I'd be offended if anyone suggested as much. Though I, personally, do not like a lot about Israel, I have to recognize the fact that it is sufficiently a liberal democracy - of course, only within its recognized borders - to provide its citizens with legitimate opportunities for influencing political process and the structure of the state. Thus, though I may dislike a lot of things about the Israeli state, my dislike is not much different from my dislike of Switzerland (another place some of my ancestors once called home - I do have crappy ancestral homelands, to think about it
) or South Korea.
Now, though Israeli existence itself, at this point, needs no further justification, the same is not true for the status of the Occupied Territories (including, for that matter, East Jerusalem). These are not part of the Israeli liberal polity and the way Israel has been behaving itself there justifies international concern. The status quo there is unacceptable for the same reason Israel's right to exist is indisputable: continuation of it is creating multiple personal tragedies. Whether the status quo is replaced w/ two states or w/ a single bi-communal Israeli-Palestinian state (frankly, my preferred option), either outcome would be an acceptable improvement. The current situation should not continue.