CK2 doesn't really have a goal besides.... not lose. Generally people set their own goals, initially being things like: don't get killed before the end of the game or take over Spain, but as you gain proficiency they expand to things like, put members of my family into all other countries leadership positions.
Usually it has built in mini-goals besides "conquer the world" like forming an empire, kingdom, etc. I got fed up with the stupid magic stacks that were added a while back so I stopped playing.
Anyways enough offtopic about ck2. I think this thread is kindof concluded to be honest, there's not much more to say besides just reposting the same complaints. I just wish the devs would acknowledge our concerns about this but I doubt they have the time to read through all of that. It's mantis'd, though. Right now I think they are focusing on what they can do in the short term, which is what you do on a daily update schedule. But eventually they'll address these concerns, hopefully.
CK2 doesn't really have a goal besides.... not lose.
And what's losing?
Having your entire dynasty die out. You could just be a count and continue playing. Ofcourse you can also switch to a completely different in-game character/country at any time, whenever you load a save you can choose. Same applies with any other paradox game.