I suspect Apple's PR team plays a role in at least some of the email responses. The emails serve as a channel that's 'official' enough for people to take it seriously, without Apple having to bother with making an official announcement or giving a reporter a quote.

It also helps make the company seem more accessible ("hey, Jobs will answer an average Joe's email, he loves us!") when in reality Apple PR is notorious for ignoring the press unless it serves them.