Is he, though? Yeah, he's famous as the guy who took the shot that destroyed the first Death Star. But everything that happened after that, everything that was related to him being a powerful Jedi, happened somewhat behind the scenes, known only to his friends at most. He trained on a planet so obscure that Yoda successfully hid out there for twenty years, he made a brief visit to a gas mine on Bespin and basically hardly met anyone, then he broke his friend out from Jabba's palace in a fashion that pretty much left no living witnesses, before going on what was already a covert mission, splitting off from that mission and going to confront Vader and the Emperor alone, an act in which, again, there were pretty much no surviving witnesses.
Most of the galaxy probably doesn't even know he was there, they assume that Vader and Palpatine died when the second Death Star exploded. Unless Luke went out of his way to make his part in those events widely known, there's no reason why they would be.