It's not a simple dislike, it's a fundamental disagreement with the existence of the character for reasons that don't involve my personal opinion of him. It's no different than if, say, Batman were to be married off in a plotline, and I said "Batman shouldn't have a wife". It wouldn't be due to a personal dislike of the spouse character, it would be because I feel the addition of a marriage to the Batman mythos fundamentally alters it in negative ways.
That's how I feel about Robin. It doesn't matter if it's Dick, Jason, Tim, or even Stephanie (whom I absolutely adore), I don't believe that Batman should have a sidekick, and that giving him one is fundamentally detrimental to the character and always has been. And I'm not alone in this. The genre convention of "young sidekick" was once ubiquitous, and has since been collectively judged as outdated and hokey. Across the board, you can see that almost no new sidekick characters have been introduced since the Silver Age, and most of them that once existed have been eliminated. The concept itself has been almost universally phased out of the entire superhero genre. Batman is perhaps the only major exception, and even he has had significant periods where the sidekick element has been removed. It's no coincidence that the most successful and respected incarnations of the character, the Burton and Nolan films, were sans sidekick. They recognized that the addition of "...and Robin!" fundamentally changes the nature of Batman and his stories, and preferred the version without.
Nolan took over a film franchise where the character of Robin had been added, and removed it. It's not unreasonable for Starlin to have wished to do the same.