So... Some new animations, a few new campaign features, and slower battles = New Game.
But a lot of new animations, several new species, doubling the size of the map, some new unique campaign features for each faction, new magic, and so on = Overpriced expansion pack?
Imagine this. Total War: Pike and Shot comes out. The first game has the entirety of Europe, plus lots of DLC.
Total War: A New World comes out a year later. It has North and South America, all the Native factions, plus some early European explorers. New campaign mechanics, new animations, new units, new cities, etc. It's a standalone game with roughly the same, if not more content as the first game. Is it an expansion pack?
I think the only reasonable answer is "Who cares?" If you want to call it an expansion pack so badly, you can have that word. But the fact of the matter is, given the information we have about it, it has either the same or more content than the original TWW base game. I paid a price for Warhammer 1, and seeing as the second game seems to have an equivalent level of content. it's entirely fair that I pay an equivalent price. Why would it not be? (Whether that's a fair price for a digitally distributed game in the first place is an entirely different, irrelevant topic)
If you can't afford more than $60 a year on video games, I feel for you. Im serious, that sucks. But you not being able to afford it is not a reason for them to lower their price.