The discussion over the "gaffe" isn't about whether he's right or wrong, it's about the nature of politics and what constitutes the kind of person who'll make a good President. The world would be an altogether too interesting place if politicians went round blurting out their every thought in public, however correct those thoughts might be.
Turn the argument about Palestine around ... let's suppose that Romney believes (as I do) that Israel's continuing settlement of the W Bank indicates that they are perfectly willing to maintain the state of conflict indefinitely. And he announces this in a speech to a large audience. Would that be a wise move?
I think there's a few different discussions going on. The issue of whether he's right has come up. The issue of whether he's overgeneralizing has come up.
And the issue of whether it's wise to tell the truth in this case has come up.
I think the answer to your question is, "it depends". Such an announcement would say at least three things. First, it would say to the Israelis that the Romney administration would be unsupportive of Israel's current settlement policy, and it might encourage them to reconsider that policy.
Second, it would say to the Palestinians that the Romney administration would be supportive of their insistence on preconditions to any peace negotiations, and it might encourage them to remain intractable and unwilling to negotiate until their preconditions are met.
Third, it would say to American voters that the Romney administration would be taking a harder line with Israel, and would expend more effort on championing the Palestinians in their dispute with the Israelis. It might encourage more voters to vote for him in November.
If that were what Romney was trying to say, and that were the encouragement he wanted too make, and he were reasonably sure it would work, then it might be wise.
But then again, it might not be wise. There'd be some backlash, of course. He'd be undermining the US-Israel relationship. He'd be enabling the Palestinian leadership. And he'd be alienating some American voters even as he courted others. Maybe the backlash would be acceptable. Maybe the tradeoffs would be worth it. Maybe it would be time to make a change in how we deal with Israel, and maybe a lot of American voters would agree.
Same thing with the announcement he actually made? What did it say? What behavior did he intend to encourage? Does he have a reasonable expectation that his intent will be accomplished? Is the likely backlash acceptable? Are the tradeoffs worthwhile? Was it a wise move?