I feel like CKIII is a good base, it just needs to be expanded and iterated on. I really like what they did with Intrigue, for example. Stress is also an interesting system, because it makes a lot of behavior that would be nonsensical in the old games, make more sense.
Its definitively their best launch in a good time.
Is CK3 vanilla more barebones than CK2 vanilla?
No, CKII was barebones as hell at the start.
Honestly, CKII only hit its real stride in the "Old Gods" expansion.
Also, CKII had absolutely pretty shit optimization and it started getting worse, until the game pretty much became borderline unplayable after a few centuries after a few DLC (I think it was by Horse Lords that this started?), until around Reapers' Due, then every version got faster.
CKIII is also pretty well optimized, I can play it with everything on lowest and all I got is a I5-3210M, 8gb of RAM and a Intel HD Graphics 4000. I did have to stop playing because the temperatures worried me (fucking 90ºC and above). If I had a dedicated videocard or a more modern internal card, I would run it no issue.
It absolutely is more barebones because they just HAD to focus on expanding the map into places nobody gives a shit about. The end result is that a nigger tribal plays exactly the same as a Viking.
Map wans't expanded that much, just a bit south until the Gulf of Guinea and all the Horn of Africa, and somewhat to the East until you hit Bengal or so.
And "nigger" tribals don't play the same as vikings. Vikings get sea raiding by culture and CBs on pretty much everyone and his mom.
Pretty sure they are going to add China in the future, its all but confirmed.