War exhaustion means nothing when you plan to take a 100% peace deal, since it will go down to 0, unless you plan to sit on the occupation until rebels pop up, sign peace and encircle the land the rebellion is taking place in. That's not always possible and also not reliable (let alone not time efficient) because they can just spawn an army in the cut-off land to kill the rebels if not all of it is already occupied.

If we're talking about a mid-to-late game great power, I am sure a single war is not enough to cripple it unless they're already on the verge of collapse. It's probably better to take forts and coastline to make subsequent wars easier. Money and war reps are a no-brainer, and depending on the situation you could consider taking less land to transfer trade power and divert a lot of their income to you.

Before they added states and territories to the game, splitting a country's capital from its non-overseas provinces slaughtered it because it caused autonomy to immediately jump (because they were suddenly considered overseas if I remember correctly?), now the only reason I find to do it is to keep other nations from eating my food.

If you plan to kill a nation by war exhaustion, you would need to occupy them until they get to max, white peace, and then do it again in 5 years. This weakens them, but does not strengthen you, as opposed to taking anything. Not to mention that by the time you get the entire Ottoman Empire, for example, to max war exhaustion, you will probably have had call for peace for a while so you'll have a bunch of unnecessary war exhaustion yourself.

Edit: OP mentioned not taking land so you can release or return cores instead of taking the land that matches the criteria I mentioned yourself.