If they own it as your client state they still contribute to your victory condition without you having to deal with the negative aspects.(also they are a neat buffer zone between you and your enemies so you have reaction time in case of war declarations sicne they first have to tear trough your vassal). If you own it, it directly influences your empires stability. especially in the lategame where more provinces = higher chance of a civil war. for example if a faction owns pretty worthless land it is sometimes more usefull to let them keep it. Originally posted by Icecream1973:No faction will simply 'offer' to be someones client state or satraphy UNLESS it is in their advantage, highly likely this could occor before you are on the verge wiping out that particular faction forever -)

Also from a strategical POV, it is complete waste of cash (your precious upkeep) to invest in an army stack (or half stack) for defense IF a client state rebels or not. In short: client states are completely useless. Client state loyalty is NOT guaranteed whatsoever, they still can rebel, which eventually can costs you a LOT more :-/ You get a tiny tribute (which does not compare to the cash advantages of actually owning that land yourself & sometimes this means because of a client state you are not able to activate a provincial edict -> costing you even more revenue each & every turn) You get 1 or of their 2 low level crappy units (mostly what they can afford or can recruit themselves & since their lands are small, do NOT expect heavy usefull units :-( You are their overlord, but this does not mean they will simply obey you & are willing to go into war with you No faction will simply 'offer' to be someones client state or satraphy UNLESS it is in their advantage, highly likely this could occor before you are on the verge wiping out that particular faction forever -)ДЄ couple of things to consider regarding client states:

Rome 2 client states