The original bible for VOYAGER listed the EMH as "Dr. Zimmerman" and described Tuvok as an elderly Vulcan who acted as mentor to Torres . . . .
Right, and in the original TNG bible, Worf didn't exist, Riker was called "Bill" and was prejudiced against Data, Data was created by mysterious aliens, Geordi was the liaison with the ship's children (I wonder if he was supposed to read books to them and say "But you don't have to take my word for it"), etc.
And it's not just TV. I got a look at the
Vanguard bible when it was just starting up, and it had an outline of maybe 5 or 6 key stories to be told over the course of the series, perhaps with other "filler" books between them -- and then they went and covered about 4 books' worth of it in volume 2 alone, and what we've ended up with since bears little resemblance to what was in the bible.
And therein lies the problem. If a TV series had a well defined plot for an x-year(s) run, with outs pre-selected for characters who needed to leave for one reason or another, then you could tell a complete story.
No, it is not a problem. Trying to make a precise plan in advance and allowing yourself no room for innovation or adaptation to reality is a HORRIBLE idea. Look at the Soviet Union and how disastrously wrong their planned economy always went. As they say, "No plan survives its first encounter with the enemy." The best plan is a flexible plan, one that lets you adjust to reality as you go, rather than one that only works if reality conforms precisely to your guesses (because that's never gonna happen).
On the whole, you don't want to be trapped by old ideas, since you never know when something better will come along or you'll make some great discovery by serendipity. So series bibles, outlines for multi-year sagas, and things like that are always flexible and subject to being revamped or abandoned. Even shows or book series that have long-term plans generally just have various key points they intend to cover and allow a lot of wiggle room about how they get there and when.
