Since there are hardly ANY in the actual game itself. Maybe put some tiny hostile faction in the DLC that only uses thrown weapons, sometimes poisoned. Wouldn't that be a different and welcomed challenge? There aren't any enemies like that in the game.
Either that, or make Thrown Weapons more common in the retail game. Whatevs...
No real point to this topic, just putting it out there as food for thought in case a dev happens to be browsing.