TD WROTE: It's the product of two different JW beliefs. First, their belief that Christ invisibly returned in 1914 and second, their interpretation of Matthew 24:45-47. Jehovah's Witnesses believe this passage is more than just a parable; they believe it to be prophetic. In other words, they believe that Jesus foretold that Christians would be on their own during all the centuries prior to his return and that once Jesus did return, he would inspect all Christian groups and organizations and appoint the "Slave" who had been faithful over "All his belongngs." in fulfillment of the "Prophecy."
This "inspection" and subsequent appointment as the "Faithful and wise servant" is their primary claim to spiritual authority. They believe that this occurred in 1919 and that they as an organization were the only ones found faithful.
It would be hard to list exactly how many secondary JW interpretations start with these two premises, but there are a lot of them. Jehovah's Witnesses believe that they as an organization were actively involved with and in many cases actually the target of a number prophecies and prophetic parallels that were realized early during the 20th century.
Without 1914, all of this would come crashing down. So doctrinally, it is very important.
MARY WROTE: However, the party line cannot be challenged: without 1914, there's no appointment and thus they lose all of their control over millions of lives. And that is something they want to avoid at all costs.
I think they could easily move the 1914 (based on 607) to 1934/1935 (based on 586/587). The toughest explanation would be the 70 years prophecy. But 1935 would fit JW history well as this could be 3 1/2 years following adopting the name, etc etc. and then turmoil in Europe leading up to WWII which was certainly more catastropic/prophetic than WWI. Although all that sets in place another date, and any date is surely a bad idea anymore. But if "this generation" can be explained away with "these [overlapping & endless] generation(s)", then anything is possible. You cannot fool all the people all of the time but you can fool 7.5 million every time there is "new light".