I don’t think it should be compulsory before they can download, but I do think the private feedback shoudn’t weight on the algorithm as much as it does now. Public reviews, tips, and even cancellations should be more important in evaluating a seller's performance.
Lately, I've been facing problems with my gig impressions because of private feedback according to my success manager, even though everything else is fine. It's frustrating that a few unhappy clients have more weight than over 20 satisfied customers. And i think that's because happy customers won't come back to answer more questions.
I completely agree with what @bethanyvo said, "Generally, a happy buyer does not bother with any emails requesting feedback that they aren’t required to be bothered with- and an unhappy buyer will want to shout from the rooftops- so the current feedback that is being collected is not an accurate representation of the sellers overall buyer satisfaction rate."