EU4's problem is that is has multiple, sometimes contradictory identities.
It's sold as a deep, detailed historical simulation game. Compared to most other historical strategy titles, it definitely is.
It's also an abstracted map painter that started as a highly abstracted board game. The abstractions inherent to this part of EU4's identity are often in direct tension with the parts of the game that aim for deeper simulation and greater historical accuracy.
EU4 is a cash cow as well, especially in recent years. As the game has aged and its developers have begun to run out of obvious candidates for new features, they've added features that have often been simplistic, ahistorical, or the basis for gameplay loops that feel artificial or self-contained. Mission trees and monuments, for instance, are each the basis for both a lot of new content and for player goals that are endogenous to the game, but not to its simulations.
The tension between these disparate features and design choices is exacerbated by EU4's player base, which is - at least to my eye, and compared to other Paradox games' player bases - unusually bifurcated between "map painters" and people who enjoy the game as a simulator of history. To the map painters, new features often represent new ways to power game; to the simulation enthusiasts (if it's not already obvious, I'm a member of this camp), new features tend to either be imbalanced power creep, or interesting sources of historical flavor and depth.
If you like power gaming, map painting, or instant gratification, you'll probably enjoy EU4. If you prefer simulation, highly integrated mechanical systems, or strong constraints on your power, you might not. One isn't better than the other, although I definitely prefer the latter. EU4 has lost a lot of its appeal for me over the past few years because of new mechanics that I feel have been increasingly ahistorical and imbalanced.
