A thing people forget about SOME DLC, is that it wasn't meant to be included in the first place.
Game developers often plan for ONE release, but because the different departments might get ahead of schedule or even finish
up way to early. Instead of those departments being idle, and in some cases not paid, they are assigned the task of creating extra content.
As the company has to put in extra hours to make that content a part of the game, it also increases the production cost,
as the hours spend more often than not exceed those paid for by the original budget.
Meaning = they have to charge something extra.
My take is that WoC wasn't meant to be playable this time around, but rather an in-game enemy with fewer and more centralized units than the other armies.(we were told 4 armies would be playable)
CA probably realized that they were able to get them ready for gameplay, and decided to go for it and use it as an advantage and pre-purchase carrot.
Regarding the extra cost: nobody has been shafted. in fact CA has chosen the user-friendly approach
If you pre-purchase, you get more than you originally bargained for. FREE. You pay the same for more.
If you dont, well you still have the option to purchase it later, so you are not forced to do anything because of a time constraint.
"But Phat, if you dont pay more when pre-ordering, how do they cover their costs with no price increase?"
Like this:
1. A bunch of WoC players (and fans) are gonna chip in now = Increased sales
2 Pre-ordering gives the advantage of getting money earlier than expected, which means they can be re-invested faster
and used to improve the business and even marketing for the original product (also increased sales)
(Example: A man tells you:" I will either give you 1 million dollars today, or 2 million dollars in a year."
If you chose the 1 million dollars you are also saying: "I think I can make 1 million dollars into more than 2 million dollars in a year"
If you chose the 2 million dollars you are saying "I CANT make 1 million into more than 2 million dollars in a year"
Most businesses will go for the early investment, because money RIGHT now is golden for a busy company with plans.
3. They know their market. A lot of players dont pre-order even with content, as they are waiting for the initial reviews before investing.
They rather pay more later, than pay less now and take the risk of a spending money on a poor game.
Total war has its sceptics for various reasons, so this is a very viable consideration.
Regarding the trailer, it is probably an in-game cinematic which got used for this instead.
CA is the kind of company who pay a LOT of attention to what their customers is expecting, so blaming them
for being DLC milkers like other companies might be a little of mark.