The simple explanation is that the 2000 election was hotly contested and the entire country was swept up in the happenings. Talk of “red states” and “blue states” became common.
In 2004, following the pattern, Bush as incumbent would have been blue. So any talk about election politics and red states and blue states in 2004 would have been confusing. Were we using the 2000 definition of “red” or the 2004 one?
It only makes sense to fix the colors once everyone has the definitions seared into their minds.
Not a Communist conspiracy.
According the the article I posted above, incumbency had nothing to do with the color destinations prior to 2000. It was all rather arbitrary, but most networks (including the ones I watched) invariably used blue for the GOP and red for Donkeys. In every election. Then in 2000, suddenly ALL the network started using the opposite color scheme.
My contention is not that it was a "communist conspiracy," but a collusion by the networks to banish once and for all the embarrassing (for liberals) Dems = Red association. Then, as you said, the use of "red states" and "blue states" became embedded in the national consciousness, and that was all she wrote.