>>58220597Because they don't want to.
Unless given a reason to feel otherwise, most Pokemon like people and the only ones who don't generally have aggressive dispositions to begin with (like Gyarados).
They likely recognize that they accomplish far more with the assistance of humans than without and the one game we've seen where they're not outright friendly was in Hisui which, before it was largely colonised and made into the modern day Sinnoh, was mostly overrun by Pokemon outside of a measly 3 human settlements.
You can also probably chalk it up to domestication of some degree.
Also since Pokefucking is Canon to an extent, they're probably drawn to people who show willingness to cooperate with and live in harmony with them. Especially since female Pokemon seem to have a propensity for being filthy humies. 
