As I pointed out in another post, using decades- or centuries-old arguments for sovereignty has been used as justification for terrorism. When bin Laden smashed a couple of planes into the Twin Towers, that's exactly the kind of argument he used as justification.
It's not about moral dissonance. It's about how hate spreads through ancient spites and grudges. The decades of failed peace attempts in the Middle East have been brought about by clinging on to these ancient grudges, and it's exactly why Palestine has had much less of a standing in being officially recognized as a nation than Israel has.