The Sticky Megathread "Warfare discussion" has 46 pages, 47k views and 916 replies. And "lack of flavor" has to be a top contender for "biggest complain" about the game.
I do agree that there are also a lot of pretty fair complaints about game mechanics too.
That is because you are lumping all concerns of that type into single complaint of "lack of flavour".
If we lump all concerns about economy into one single complaint, it would easily surpass lack of flavour. Ditto for many other areas of the game.
Now, I would agree that there is a lack of flavour but the way to deal with it is throught expanding the mechanics of the game.
Let's imagine that naval bases had range that affects warfare and colonization - suddenly you have a very different situation regarding Africa. If you're playing Russia, you can't really throw your weight around in Africa and colonize just as well as Britain and France, for example. There's some flavour right there.
If straits were close-able, power projection outside Black Sea for Russia is limited. So, you have to get Ottomans on your side or take control of Constantinople.
Stuff like that would add depth and flavour to the game.
I am fully aware that a lot of people want new decisions/journal entries/events for specific countries and such DLC's will happen, I just hope devs don't allow themselves to think that those DLC's are replacement for depth.
For example, I want better mechanics to represent dealing with internal turmoil while trying to modernize. I don't want Japan DLC that adds some unique things and solves it for Japan, while I'm still gonna be stuck with old, poor mechanics if I choose to play Siam.