Feedback wouldn't necessarily be very useful. The feedback might be a meaningless number such as '42' in the Hitch Hikers Guide to the Galaxy Deep Thought (which doesn't really explain the result of the question).
There's probably too many rejections to give any feedback. I mean if there were 10,000 to 20,000 groups that applied it would be impossible to send a reason in the email to each group. Besides it all comes down to a numerical rating (sauce for the goose). Kudos to the bird with a golden egg.
I think two years ago, the last they posted their numbers, there were 421 applications. This year, I'm just guessing, but likely somewhere between 2 to 4 times that.
They are no longer posting their numbers, so don't ask.