I've always found it rather impressive when artists manage to make naturally unsexy character designs sexy.
In this case, they made the very blocky Minecraft design for Alex just as alluring as the other girls, though the really cute face helps a bit there.

Kazooie stares at Mii Gunner:
"Bitch, you're not a DLC character!"

Mii Gunner:
"I'm wearing a DLC hat!"