Slightly crooked teeth is considered highly moe in the idol world, it makes the idol feel more like a genuine human and relatable
At least jaypee told me so once
Other than that, I think it's a case of Britbong. Great dental care is available, buuut nobody really cares about braces. Here almost everyone gets told to get braces "just because" so we can all be as aesthetic as possible and not bring shame to our beloved king.
Isn't he kawaii
I already had even teeth, go me!