However, once you understand these events, you'll quickly see a problem: Without the mod, you don't even know these events are there, unless they fulfill the trigger condition and pop up. And that isn't obvious. For example in my current Byzanz run, I now see that there is an event in the case that I conquer Athens and integrate it. However, I chose to vassalize Athens and annex it. So I never triggered the integration condition, and never saw the event.

If you look at the unique events and their triggers, it becomes obvious that the developers assume the player will play a country in a certain way. It is only logical for the Byzantine Empire to want to reconquer all of Greece. However, there is also an event that triggers if the Byzantine Empire owns both Constantinople and Venice, and not ever player of the Byzantine Empire will want to meddle with Italy. It is easy to imagine a run in which the player decides to turn eastwards instead of going the historical way of trying to reconstitute the Roman empire. Any player who plays any country in a more original way will end up triggering fewer unique events for that country.

That makes me wonder how attractive the Europa Universalis V DLCs are going to be. Already at the base, if you don't want to play the Byzantine Empire, you don't need the first DLC, Rise of the Phoenix. But even if you buy it and play it, you might not see a large part of the content. There is at least a risk that buyers of the DLC will be underwhelmed, because too much of the content is invisible to them.