Palpatine probably defiled the Jedi Temple. Turned it over to Vader, or his other Dark Side acolytes. Filled it with trophies of the Purge. So Luke would've avoided the place if he was ever in the neighborhood -- to him, it wouldn't be "the Jedi Temple," it'd be "Vader's Palace," or "the Imperial Museum -- Jedi Coup Annex," or just "the site of the greatest massacre of the Jedi in four thousand years."

That's assuming he ever was in that neighborhood. That region of the city might've been destroyed by the Lusankya's exodus shortly after the Alliance/NR took Coruscant. Even if it survived that, it was probably destroyed during the Mutiny, the Imperial resurgence and interneccine warfare leading up to the events of Dark Empire. Or maybe Luke's Star Destroyer landed on it, in a sort of ironic twist on Force piloting?