Automatic rebel suppression, as already mentioned. It's pretty much useless if you care one iota about playing efficiently.
Another great example is CK2's automatic title distribution feature, which ruined many a person's game and was apparently designed with the same mindset.
Rebell Supression needs an update so that the armies try to reduce Unrest actively imho.
Otherwise the feature was good when the rebells (non event ones at least) did spawn randomly all over.
I still use it i n remote places when i can't be bothered with the revolts at all.
The "make Rebells Attacker" thing is in my eyes an exploit and should be removed from the game or changed otherwise to remove its exploitiness.
I celebrate the things Paradox does well, and grumble about the things they do poorly. I'm not going to celebrate in advance about a feature that seems similar to things they've done poorly in the past. If it does turn out a great, smoothly-functioning feature, then I'll be pleasantly surprised—but I'm not holding my breath.
If that makes me a pessimist, then thank goodness I'm not an optimist.
Expecting the worst makes you an pessimist, wait and see with a cautious outlook makes you a realist.
Maybe i missjudged your post and you just haven't much expectations, which I, with PDs track record on semi-developed/broken features can understand.