In an interview with the Washington Post, George Lucas said the change between theatrical and special editions was to do with Han’s principles.
“Han Solo was going to marry Leia, and you look back and say, ‘Should he be a cold-blooded killer?’” Lucas asks. “Because I was thinking mythologically—should he be a cowboy, should he be John Wayne? And I said, ‘Yeah, he should be John Wayne.’ And when you’re John Wayne, you don’t shoot people [first]—you let them have the first shot. It’s a mythological reality that we hope our society pays attention to.”