>>28200075Is this a serious question? They do it for marketing. Children respond better to a friendly monster that can pose and emote like a human.
Exceptions can be made if it's a lot bigger or smaller than a human or has a gimmick that wouldn't work while standing, but in general, bipedal monsters sell more toys. It's why Pikachu was redesigned.
You can make polls asking normal people (not /vp/ anons who will pick the opposite of their preference out of spite) their favorite starter pokémon from each generation, and there will be a positive correlation between bipedal stages and popularity for at least four of them.
