Honestly, I like every change that came with Conclave except for infamy/threat, which I'm lukewarm about (the shattered retreats were pretty wonky at release but were quickly patched and are now pretty reasonable). The threat mechanic seems a little arbitrary as it is now, but if I run more games and find that it puts some brakes on the major blobs as intended then I'd call it a win for sure. Meanwhile the council mechanics have me thinking much more carefully about appointments (it used to be a total no-brainer, but now it plays a major role in realm stability and your ability to get laws through), it's added much-needed new layers to vassal interactions, and the new laws gives you a lot more interesting combinations and more mid- and late-game policies to strive for (prior to Conclave I'd usually get the laws I wanted within a few generations and then never touch the screen again).
When I play I'm usually more interested in setting up a midsized realm with some distinctive or interesting features ( unique mixes of culture/religion, laws, strategic location, etc) than just blobbing to the ends of the earth, and Conclave gave me some pretty cool new features to mess around with. I really feel like it's only a loss if you have an extremely narrow focus on expansion, and even then the impact of threat only kicks in if you've got a pretty large realm expanding at a fast rate. The game can run for up to 700 years, there's really no need to be in that big of a rush.