TLDR: Weekly rotation of DLC units in MP, see "Idea" at bottom
First of all let me start off quick in appraising the new DLC! This is the first time in WH1+2 that I have been looking closely almost daily for more information with the new DLC, pausing videos to check out units stats. I like the SP experience in campaign, but I for sure wouldn't nerd all the information so much if it wasn't for the MP in WH2.
I have the feeling that CA have the impression that MP is not worth alot of time and they are probably backed up by their user activity data. So here I am trying to explain to you why this data is misleading, please read on.
I got two mates who plays SP and co-op campaign constantly. They are not keen on the multiplayer aspect of things, mostly because the gap in skills there is coming directly from fighting AI against human players. This is obvious, and here the game needs much better ladder system and other stuff, so you won't get matched up against a "pro" in your first or second game of MP.
After getting them to watch some of my MP games, while I was playing, they got really hooked on MP. They just needed that push. Is like they got the games worth back AGAIN from new, after hours of hours of campaign.
For me starting in MP, it felt like learning a new game. I now know almost all mechanics in game. Doubt most SP campaign players know basic stuff that AP damage is actually "pure" damage, the difference in normal/magic/fire attacks and resi, how big of a role attack-animation plays (and similar like how Halberd units hits slower than regulary inf units), and so much more.
I understand MP is not for everyone, I gotta say though I reaaallly think this game have some insanely amount of potential on the MP aspect. I will always enjoy the new content, booting up a new campaign, but first of all I would never buy all DLC's and secondly I would not play as much if it were not for MP. I think many people, with just a small push, would love MP.
I always hated (found it trivial) most of micro in pc gaming, so I never played stuff like star craft and if I played a game like total war I would never ever use units like Chariots or skirmish units. Now I not only use these units in MP, but in SP too and having fun with them. I think micro is just a barrier you need to learn the basic of, to be able to have fun with.
- This is something of a barrier though, several people won't play games with a high micro skill cap, which Total War in MP always will be without making it a mobile game. How to make it easier for people to learn I don't know....
Okay that was my take on why some data will mislead you into thinking alot of people would have 0 interest in MP and why you could sell even more content if you used resources on the MP part of the game.
Following is an idea to make it possible for people to try Total War Warhammer out in MP, without having to be a TW nerd and own all DLC's.
Quite a few games have this system actually, even those F2P/P2W games. It's made to get more active MP players and to get people hooked on your product too, kinda win/win for the seller and consumer.
You could do a weekly rotation between the races where you unlock ALL dlc units for that race. As long as you have the base games (WH1+2), you are able to be a part of this rotation and play the given race that week in MP. If you want to restrict it more, lets say every weekend or smth.
I don't think you are losing anything towards the players who only play SP/campaign, and you will open up for many players to play MP who would have never bought all games+dlc anyway since they probably wont play SP (but now might buy the content for MP, if they like what they see in MP).