I am going to try this again, while I am a little more awake in hopes that it might make better sense:
[spoiler]
When the Ravers go after an entire race, they go after what that race holds most precious, to corrupt it or otherwise detroy its value.
With the Unhomed Giants is was their children and their hope of home.
With the Blooguard it was their service to the Lords.
I think with the viles it was their creativity and love of beauty. The Ravers tried to make both look worthless. Perhaps the Ravers were a little less successful with the viles. The demondim seemed like evil dudes, but the waynhim have always been good, and the ur-viles seem to be good guys in the Land right now, too.
[/spoiler]