But "Norse god comes to Earth", "Charismatic playboy builds kickass robot suit" and "extremely sexy female assassin" are much easier sells than "female cousin of the Hulk beats up thugs in a one piece bathing suit".
It's not that I think someone couldn't make She-Hulk totally work in one of these movies, or that I wouldn't love a She-Hulk movie that maintains the spirit of the character, or even that the character just isn't popular at all, mind you. I'm just saying why Marvel likely hasn't even considered introducing She-Hulk into the MCU yet, especially when they have more viable properties like GotG and Nova, Black Panther, Power Man and Iron Fist, Dr. Strange and even Ant-Man already in the pipes.