In-universe, the story of Luke redeeming his father (who was basically space Satan) was super fucking impressive, and spread far and wide. They talk about this in TLJ.

Also, from a story point of view, the smaller more emotional climax of him redeeming space Hitler is far more cathartic and interesting as an audience (at least to me).

If Luke replaced Wedge in the final battle and blew up the core of the Death Star, he may have made a more apparent strategic difference, but his arc from the whiny farmboy in the first movie would be incomplete. He wouldn’t have used any of his new skills or anything he learned as a character if he just blew up the place.

If I was gonna change anything about the Luke stuff in the movie, I would have made the Emperor actually tempt him a little, because nothing he offers actually truly budges Luke.