This is a really important point to remember for interviewers. The interview process isn't just to help you find good candidates, it can be a great branding/marketing vehicle as well. I've gotten many good people from former candidates who enjoyed our process and spoke highly of our team.
I wouldn't have just stopped replying to emails though. An interviewer should always reply, even to politely decline. And it can help to add a reason why you are declining a candidate too, since it can help them improve and perhaps return for another interview in the future (I've hired a few people that I originally passed on too).