>Israel is the only country whose mere existence seems to require justification
Well, that's because most other countries weren't plopped down in the middle of an inhabited region, resulting in decades of violence and oppression that, and this part is critical, continue to this day. The US also shouldn't have been plopped down on the land inhabited by American Indians, but since the dust from that has mostly settled, it serves as a less poignant example of the dangers of nation-building. The lessons from history here should be obvious, but for reasons of nationalism and religion (by which I am referring to American Christians), those lessons are being obscured.
>Framing Israel's political problems as if they can be easily solved by not having an Israel certainly looks analogous to solving a Jewish problem by not having Jews.
I guess they look analogous? If you squint? I mean, for one thing, saying that establishing Israel was a mistake is not the same as saying that Israel should be dissolved.
For another thing, what "Jewish problem"? From context, I guess you're talking about the Nazis, but that "problem" was Hitler's accusation that the Jews were responsible for WWII. But unlike "Israel's political problems" (as you so delicately put it), that problem was a fiction.
Finally, while it clearly would not work to dissolve Israel at this stage, the problems with that plan do not significantly intersect with the problems of genocide.
I mean, I'm trying to be charitable to your analogy here, but it sounds to me like you're saying that people find "Israel shouldn't have been established there" offensive because it calls to mind an utterly false analogy.