One of the things Ron Moore said was that they had revealed so much...that it wouldn't be fair to the audience not to bring those things to conclusion.
Here's the quote:
"And by the end of the season, we had taken that moment and moved it to the revelation of four of the five Cylons, and one of our characters had actually been to Earth and seen it," Moore notes. "But that was sort of the moment where we started to feel like, if we don't start to pay this off and don't really reveal those secrets and move in that direction, we'd get to a place where it would feel like we're jerking (around) the audience."
As sad as I am about the show coming to a close, I do appreciate the decision he made there.