why does it matter? they're not the experts on your business - you are. unless they're buying your product, keep calm and carry on - the best validation comes from customers.
Isn't it obvious? Presumably if you cared enough to apply, you care enough to hear why you didn't get in.
It's the opinion of one (smart) group of people who are judging your idea against everybody else that applied.
It's worth something, but your customers' opinions are worth more. Go get those!
No feedback is not really helpful to anyone. All anyone knows is they were rejected for potentially arbitrary reasons.