Email inquiries are short cuts for the ignorant especially when dealing with a service. They have not yet figured out that a DJ service, though on its surface is a commodity (sound system, music, warm body with lips), is really a talent/service based enterprise.
Emails are cold. Emails are cover ups. Emails are lazy. If I'm not one of the cheapest of the price quote responses, the % of responses is fairly low, closing a sale even lower. If I respond with anything other than a price, the percentage of responses seems almost nothing. Perhaps it's because of the actual content of my response. Don't know, but even responding seemed to be a huge waste of time except that it does keep my name out there. For that reason alone (keeping my name out there in every instance possible), the now streamlined canned (yet personalized) responses keep going out; even for the ones where I'm already booked.
Could it be email shoppers can be impressed with lots of gear size, shape, brands, and quantity talk and information, cold callers can be impressed being entertained on the phone, and the ones that already know your name no matter how they contact you, are the ones who will actually book? I think so.