He`s got the longest association with the role. He created it, after all.
No need for "poor Jason" here, they obviously like him for multi-appearances and his profile as Red Hood only keeps growing. By proxis even his profile as Robin is being extended with the Arkham games and the possible role in the upcoming movie.
So what if they liked him less as Robin than the other mains? Big deal. I prefer they like him best where he`s the most marketable.