Creating a credible kid sidekick isn’t an easy task. The basic concept is always to give the younger readers a character they can personally identify with. The problems there are legion. For starters, readers want to be Batman, not Robin. Furthermore, the sidekick has to have the correct amount of competence. Too much and the character can outshine the hero and readers don’t like that. Not enough and the sidekick will need too much constant rescuing. And then there’s the issue of older writers trying to write “hip” dialogue for a character much younger than themselves, as was the disastrous case of Snapper Carr when he first arrived on the scene as the Justice League’s sidekick.
Good sidekicks and younger characters can be done. But for every successful Robin, there’s probably three or four (at least) Danny Chases.