I definitely agree that if Hook had continued as Rumpel’s nemesis, the true love of Milah aka Neal’s mother, Captain Hook of Neverland, pirate connection, cohort of Cora, then maybe there could have been something there. The thing is that all of that was just wiped away at the end of Season 2 when they changed Hook’s character. In Season 2 he was one character and then suddenly they got the rights to do Neverland as an arc and suddenly they rewrote him, then reintroduced him as this completely different character in Season 3.
Hook is boring and serves no purpose, has no connection, does nothing for the characterization of the show. He is just there to stand next to Emma and sometimes to serve as a place holder in scenes of exposition when necessary. He is just there so that the important characters can sometimes talk to someone, aka the audience, while still keeping things from the characters that matter. Emma and Belle and Henry and Charming talk to Hook because they are hiding things from other characters or figuring out things about the relationships in their lives that matter and because sometiens there are things the writers need to tell the audience. They could replace Hook in any of those conversations and it wouldn’t matter if it was him or not. It could be anyone. Except the ones about Emma and Hook’s romantic relationship, which as others have said, not everyone finds interesting.