Just wanted to bump this. It would be such a huge thing to have. I know of many people who stop queueing Feast when they get on a losing (or winning) streak because they don't want to affect their rating any more. If they are on the losing end of it then sometimes they quit Feast altogether.

Unranked would:

Allow for a stress-free version on Feast and give everyone an alternative during the times they aren't feeling up to ranked.
Give veterans the opportunity to group up with and help new people, without the rage associated with rank being on the line.
Give new players a chance to practice in an environment where more experienced players would be helpful, not resentful (see #2).
Lower the entry barrier that is currently associated with PvP.
If #2 and #3 work, it will also improve our PvP community drastically as the amount of brand new people in ranked would likely decline drastically, and so would raging.