The 607/587 thing is critical to the authority of the WTS and to its Governing Body. They claim to be the sole earthly representative on earth of Jehovah's Government that began to rule towards earth in 1914. That date is based on a calculation that includes 607 BCE for the destruction of Jerusalem. This is the reason WTS apologists rise so strongly to defend that date. See how much effort their JW doyen Furuli expends on the subject.
I'm not saying its not an important piece of information. I'm saying its not an important concern to the JW Brass. To be a problem two things must exist:
1) You're wrong (check)
2) People must have a way of being confronted with the fact that its wrong.
You dont learn about the destruction of Jerusalem in school. There are no TV shows about it. No one in the general public knows (or cares) when this happened. So there is no reason to ever really question the date... therefore it is not an important concern.