The "prophetic" books of the Bible contain lots of wild imagery and vague predictions. For example, Daniel describes various periods of 1260, 1290, 1335, and 2300 days. Revelation contains discussions of a variety of wild beasts, trumpet blasts, etc. While the meaning of these items are a source of vigorous debate among Christians, the WT Society has put forth official positions which, of course, must be accepted by JWs.
Of course, a dirty little secret is that most JWs have no idea what the Society's interpretations of the 1260, 1290, 1335, and 2300 days are. They would probably be surprised to know that:
- The 1260 days of Daniel 12:7 represent 1914-1918
- The 1290 days of Daniel 12:11 represent 1918-1921
- The 1335 days of Daniel 12:12 represent 1922-1926
- The 2300 days of Daniel 8:14 represent 1938-1944
When you read the explanation in the Society's Daniel book, the explanations are laughable--especially the 2300 days (hint: it involves some WT articles and a change to the Society's corporate charter). And then there's the embarrassing doctrine about the 7 trumpet blasts of Revelation being 7 district conventions in the 1920s. As a believing JW, I often wondered: why does the Society feel the need to come up with an explanation for everything? Why can't they simply say they're not sure?
I'm sure there's not one single answer to this question. For example, arrogance no doubt plays a part, as does inertia--once a doctrine has been taught for decades, there is some reluctance to change it unless a compelling need arises. But I expect there are some folks in the GB/Writing Dept. who are not convinced by these interpretations, and would perhaps prefer a more reasonable "we're not sure" position.
I think the main reason is the Society's need to project "unity" of worship. If the Society simply said "we're not sure what the 2300 days of Daniel and the 7 trumpet blasts of Revelation represent," it would open the door for Witnesses to speculate, which would undermine the perception of unity. We've seen this already with regard to the identity of the King of the North (here, the WTS was forced to back off its interpretation because of changing world events in the 1990s and 2000s).
This unity/uniformity of belief is one of the factors that the Society uses to "prove" that JWs are the true religion. How many times have you heard Witnesses brag that they can go to a KH in any city in the world and the same thing is being taught. This is because the Society has an answer for practically everything--including the wacky prophecies of Daniel and Revelation. As long as there's something "in print" about a matter, every JW is required to accept it or else be shunned.
That's my theory, anyway.