I think their are plenty of Imps in Rivellon, but they're mostly very tribal (I remember fighting a lot in Divinity 2 and Divine Divinity). Orcs dies mostly out in Divine Divinity, but those were the neighbours of the Dukedom of Ferol (which was called Rivellon at the time, before Rivellon was the name of the world ... it's complicated :D), but I guess there are a lot of tribes around, who just love to live the wildlife and can't be bothered to create a bigger empire like the Dwarves, Humans and Lizards did.
As for not appearing in the games: I guess since we had no Origins for them, Larian didn't want to implement them more in the game, so the mainconflict between the major races doesn't get watered down?
Last edited by Zelon; 15/10/17 06:45 PM.