I see the All-Star game as a showcase of the best talent the league has to offer RIGHT NOW. It's supposed to be a fun and entertaining fluff match for the sake of the fans. A distilled version of all that is fun and exciting about the game in this moment in time, at least from a casual fan's perspective.
Kobe is an icon of the sport, that's true, but hey, give him a career achievement award or something. If he's on the court, he makes the game less fun to watch. Period. He stinks, he knows it, and he doesn't care.
Kyrie, at least, is one of the game's young stars, and when healthy he has flashy moves and is appealing to watch. He represents the present and future of the league. Kobe is entirely in the past.