I’ve always thought that the Jewish people avoided going onto the Temple Mount in Jerusalem to avoid angering the Palestinians. Well, I was wrong (at least when it comes to the zionist segments of the population.) Here’s the reason, according to Haaretz, an Israeli daily:
… most rabbis prohibited Jews from going to the Temple Mount because no one knows for sure the exact location of the Holy of Holies, and the concern that today’s Jews, considered “impure” by Jewish law, would enter prohibited zones.
However this opinion certainly doesn’t go unchallenged, from the same paper.