"The Courtesy of a Reply is Requested"

. What ever happened to our general adherence to the dictum "Every legitimate communication deserves the courtesy of a reply"? I cannot figure out any pattern to it. The highly ranked and the low, professionals, businesspeople and students, public officials and private individuals, recipients of compliments or complaints... it seems to make little difference in predicting who will reply and who will not.
. The "History" feature of some email systems has long promoted accountability because one can see if the recipient has opened your message. Apparently that is still not enough motivation for some people who are not at all embarrassed by the fact that you know when you have been ignored.
. Here is one no-cost, high-value improvement we can all make to the general level of cheerfulness of our world and of our workdays. Resolve for the New Year, or at any time of year:
I will reply promptly to all legitimate communications, even if just to say:
"Thank you for your message. I will seek an answer and write back as soon as I have it," or
"Thanks for the suggestion. Your feedback is appreciated."