First, because your vision for CK3 and the way you may enjoy more the game can be different from the devs' vision.
Second, OBfusCKate hides a very significant amount of information that you dream about. If it fits 80% of the bill, certainly it is a significant improvement for your enjoyment of the game as a whole.
Third, again, because the devs might have (certainly have!) other vision for their project. Much more intriguing than this hidding stuff that might certainly hurt sales - see total numbers of subscriptions for both mods! - is the example of
Nameplates where the simple and informative object of the mod is to add the names of characters to the event windows. Even such a simple job (it consumes at most five minutes to do it!) did not merit to be included in the main game.
Where is your data to backup your claim the
"company would make so much more money from the game if it was harder"? Do you believe that for some reason you are alone smarter than a team composed of dozens of talented persons evaluating the product they have in hand? Maybe it is just me, but I plainly doubt your business acumen...
If I am wearing my cap of investor, I can only commend the way Paradox so diligently maximize its profits. With my gamer cap on, I also root for something more challenging, also knowing that the most complex mod - in my knowledge - that turns the game harder only have about 14000 subscribers. So, the only metric I have available doesn't sit very well with my tastes as a gamer. Counter to this, I can only add the fact that other Paradox products don't have this easy approach to design, being more challenging games, so it seems significant profits can also be enjoyed by harder designs.