Donald and Walter looked like two high school algebra teachers who started a band. That much charisma. They were music dorks. In interviews, they came across as if being successful was some hassle. Plus, they were super smug know-it-alls. The tone they communicated was everyone else’s music sucked. This superiority even came across in their lyrics (turn up the Eagles. The neighbors are listening).
What was abundantly clear was these two didn’t care what you thought of them. Becker and Fagen wrote their weird songs and let them speak for themselves. They routinely dodged questions about song meanings giving smart-ass answers. They also didn’t explain who wrote what, nor did they provide credits as to who played the instruments on their albums (until Aja). Mostly you got the sense that these guys were just two super-talented dicks. Which, given “Steely Dan” is a reference to a dildo, is quite fitting and ironic at that same time.
Despite all this, they made undeniably great music that endures today. They are in the Rock and Roll Hall of Fame.
In the end, I think you dislike them because you want to be them.