Why are the main protagonists in the main stream anime, stupid?

[Claraviolet]

I don't get why to be honest.
Is it because they might attract attention? Or is it because they try to cover the overpowered character with some stupidity mixed, so that they won't be hated in the long run?

 

[Demon_skeith]

They are either dumb, cool or laid back, it has to be one of them but I do agree that stupid is over used.

 

[Blackangel]

it's a charm and the authors think people would fall in love with the main protagonist if they are stupid. i don't fuking get it at all but i don't think it's a fetish.

 

[Kaname]

If they are perfect in every way people would get bored of watching them man.
I wouldn't watch a perfect MC