Total internal consistency isn't necessary, and can actually be harmful to a show if you take it too far. Sometimes it's better to conveniently paper over an earlier mistake. But this is just plain laziness in writing, and it hurt the show by removing a lot of material for conflict and drama.
Ronald Moore was a big driving force behind the new BSG and previously did a lot of work on various Star Treks, including a brief stint with Voyager. In many ways, BSG is "how Voyager should have been."