Letters and correspondence were sent but took time and who knew if the person received it or would even write back. Telegraphs were expensive and resulted in a shorthand that humorously enough has come back with modern character limits on text messages and tweets. As with modern technology, who knew if the recipient got it and when they were going to reply. Telephones allowed instant connection from distances, but the person had to be there on the other end until the invention of answering machines, to which return calls were always a curiosity of when. Then the internet and e-mail came along which allowed us to not only easily and quickly send along messages but include and ask for a wealth of information previously difficult to communicate back and forth.
Along with Outlook meeting invitations and Google Calendar, Evite and Facebook events made it easier than ever to plan group outings. But the "not yet replied" column always stayed full as people just didn't seem to bother to reply. Cell phones and text messaging suddenly created an instant line of communication with anyone anywhere, as they carried their communication devices with them everywhere they went! Suddenly we were bombarded with a huge influx of communication requests. A hyper-connected always on society that could communicate easily with anyone anywhere. But along with this connectivity the desire to respond in a timely fashion (or even at all) seems to have fallen by the wayside. For messages we were hesitant for whatever reason to respond to in the first place we suddenly were loathe to have access to 24x7, and a huge pushback started to occur.
Think about the way we use text messaging in our daily lives. It's like a condensed version of voicemail/telephone conversations great for when short and simple messaging is required, and a hyper version of e-mail at worst. When you send out text messages, do you always get a response back? Even if you explicitly asked a question of the recipient? Even if you're lucky enough to get a response, was it immediate? Maybe it was hours or even days later. It seems as if the common reaction to text messaging corresponds with its rapid communicating capabilities - the easier it is to communicate, the lesser importance we place on the necessity to respond or act on it. What's your own policy on returning messages? Do you generally respond immediately? Hours or days later? When you're good and ready? Do your own expectations for others to respond sync up to your own responses to others?