everything doesnt have a reason actually, they never explained why Dosu covered his face

they're yet to explain why Kabutos eyes changed back in the forest of death and its been more then a year or so since it was shown in the manga. Also they havent mentioned Obito or whether he/she was actually a nin.

They havent shown Anko again even though she was Orochimarus student and has a cursed seal herself, and they never explained why Orochimaru stopped using her.

They didnt explain exactly what clan Haku was from either do you get my point? theres alot of unexplained things in Naruto

they're also yet to show the reason why Sakura has an inner self too

i think its the mysterious things that keep Naruto interesting, it keeps us speculating.
if Kakashi's past is explained then it'll change the way we view his character, i dont think Kishimoto is about to that unless it directly effects Naruto in some way