i think pdx should make control under 70 rapidly increase revolt risk along with the current lower income, to make owning low-control land directly an actual detriment
this will encourage distributing conquered land to vassals, establishing tributaries and straight up allies in the early game until you get the technological advances (and gold) that would let you increase control enough to make conquered land, well, controllable
if vassals and tributaries are balanced to be challenging to make loyal long-term, then altogether you'll get a game dynamic where every large power early on will pretty much have to be a feudal one, slowly centralizing and revoking vassalatic liens as time goes on and crowns accrue power (as was the case historically)
rapid conquest would then become harder to justify, and even if conducted would still necessitate empowering local rulers as vassals or even make establishing relatively hassle-free tributaries the better way of extracting value from war

what do you guys think