Guys, do you actually think its Craig responding?
Similarly, when emailing Tim, do you think its him responding?
These guys are far too busy to be sitting at a desk checking the thousands of public facing emails they must receive, or even respond to them. It's most likely a dedicated team that filters through emails, responding where a response is required, and sending anything of more major importance to the correct teams. I very much doubt Craig or Tim are sitting at a desk responding to public emails when they have thousands of employees under them.
I get what you are driving at, but many in the company shared Steve Job's ethos about engaging with users. It's such a simple thing, and like with the YT videos Craig has recently been involved with, it is Apple reaching out in ways it can't do at present (and clearly was doing before). Sure they don't read everyone, but what does happen, and it's been confirmed, their team will flag emails they think worth responding to, based on set objectives, issues etc, and forward it to them and they'll respond.
Steve was known for trawling through emails and picking some to reply to, having had one responded to by both Tim and Steve, I can assure you it happens. I've also had emails that have been designated to certain teams to respond to, but those don't make the news!