I've had a couple of rejections now and asked just those things, but got crickets in response.
The naive in me thinks that "recruiters probably have massive inboxes clogged with inbound applicants and didn't see your message". The cynic/tinfoil thinks "there's probably a 'reject' button that once pressed sends the canned 'thank you for your time' email while setting up an email filter to send your messages straight to the spam folder".
I guess reality must be somehwere in between. What are your thoughts? Is there any industry standard in this, or is it really up to different recruiters in different companies at different times do different things?
Recruiters will put a candidate to the bottom of the pile if they flunk multiple interviews, or badly bomb one. That embarrasses the recruiter -- they lose credibility with their actual customer (the employer) if they keep sending unqualified candidates and idiots who show up for interviews late in gym shorts and a Metallica t-shirt who don't know what the company they're interviewing at does (actual experience I had). A good recruiter will tell you how to do better next time. They probably won't send you back to the same employer for another try right away, though. A good recruiter can prepare candidates for the interview, the bad ones just throw mud at the wall to see what sticks.