Keep in mind who Revelation was written to (7 churches located in Turkey) and what it was about (
"things that thou hast seen, and the things that are, and the things that are about to come after these things
"). Other things John wrote about were soon to take place (
"for the time is nigh!
") as 2,000 year later would not be "nigh." These churches in Turkey were under heavy persecution by the Jews living there, the Greeks and the Romans. Thus John wrote to instruct and comfort them because upheaval was the order of those days throughout the Roman empire, not just in Israel.