Responding To Blog Comments = Good Business Practice.
Sometimes a comment or an email response gets lost in the shuffle. We're human and sometimes we miss something, but ignoring comments and emails is not a good habit to get into, especially if they're tied in with your business. It's poor business practice, doesn't look professional, it conveys rudeness and poor manners and simply doesn't make you or your business look good.
If, for example, you receive a katrillion blog comments a day, at the very least, popping on and leaving a comment indicating that you can't possibly respond to everyone, but that you appreciate the comments and their readership, is a nice and courteous gesture.
Readers love to hear from blog authors and they'd be impressed that you acknowledged them or addressed them specifically (think about how you feel when a blog author responds to you). When you have time, visit their blogs and leave comments. It sends a wonderful message to the recipient that you're kind, friendly, mannerable, inviting and appreciative. It also keeps your lovely readers coming back for more AND more likely to share your goodness with their circle of loved ones. :)