The problem is always how to develop that to please everyone.
Long wall of te...yadda-yadda regarding the pro's and cons of the different DoW games follows...
See DoW 1: (note: I didn't purchase the last Expansion so I don't know what that did to the game)
They had a Story Campaign for Space Marines and added over the course of 3 Expansions a lot of other Armies, but only had one true story campaign the Space Marines. Albeit I played Dark Crusade a lot back then (it added Necrons) the campaign basically watered down to a skirmish-after-skirmish campaign with an overarching map with persisting troops, buffs, etc.
Story-Campaign: Only Space Marines
Other Folks: Meh (Skirmishes only and only beginning with second expansion)
Variety: A ton since they added a lot of folks (but no tyranids)
Now take DoW 2:
Less RTS more Moba stuff but thankfully still RTS (more like RTS-light+RPG-ultralight)
Story Campaign: Base Game and first Expansion again Space Marines only
Other Folks: Got a story campaign in expansion 2 but it was a carbon copy of the Space Marine Campaign, at least I found that pretty insulting and lazy development.
Overall I liked DoW2 more for 2 reasons, the story Campaigns were ok (IF you like Space Marines that is) the Tyranid thread was very very fun in the overarching Campaign plot (the Chaos one in the first expansion was meh...)
And second reason: "the last stand" Boy that was fun. I spent tons of time in that mode, more than in the story campaigns and skirmish/ true pvp alltogether.
Even now I log into it once or twice a month and try to get a game rolling (needs 3 players) even with only 3-500 people online it works most of the times.
I liked the "last stand" so much that after seeing the first impressions, reviews and youtube videos of DoW3 I vowed to only buy it when they finally do a DoW3 Last stand mode.....which seems to be never.
The new game seems to fall flat on its face on a lot of ways, no last stand, forced three way royal in the story campaign, no fun dlcs no additional armies....
It seems to be Relics Mass Effect Andromeda/Star Wars Battlefront 2/Shadow of War...
Otherwise some people also seem to have way to high and unrealistic expectations.
See Battlefleet Gothic: Armada
Everyone and its mother cried for Story Campaigns for orks, Eldars, Chaos, Space Marines, Tau.....I could understand Chaos but none of the other folks were crucial and overly involved in the Gothic Conflict (again aside Chaos) which the whole story campaign is wrapped around.....it seemed to be too much of a bother for everyone to have a short read about the conflict on lexicanum it seems. While I truly enjoyed Campain mode in BFG:A I was constantly shaking my head to all the "gimme" crowd.
That at least seems to be solved with BFG:A 2.....lots of folks and an conflict which pretty much involved every faction that exists in wh40k
but...which propably will end the same way DOW1 did with dark crusade (which is ok) or DoW2 Retribution (which is truly truly bad) a skirmish-style campaign mode. Light on the exposition and story/lore of the conflict depicted.
Also balancing...if Relic of new has problems balancing just 3 Armies in their latest DoW, how will Tindalos manage 12 armies in BFG:A2? Especially after the rocky release of Eldar/Orks/Tau in BFG:A 1?
Balancing always loses out the more factions are involved.
Hard to please everyone....release to few factions, the gimmes begin to cry, release to many and everyone cries OMG-balancing sucks!
If I had a say in it I definetly want good developed single-player campaigns more than a ton of watered down "dynamic campaigns" for every army. If I only get one campaign than so be it, but that one be better damn good! (BFG:A and DoW2:Vanilla come to mind)