I think most of us, atleast I am, are mainly against this simply because we don't have that many great CBs to start with. Next to Chiellini you have 1 really old, but good defender and a also pretty old, rather crappy one.
They all like to get injured, in which case we'll have to change stuff around even more by playing Cáceres in the middle, and Grygera on the right. Atleast Ariaudo will be somewhat accustomed to playing with the other CBs, we have absolutely no idea how Cáceres would do, since his positioning isn't his strong point.
I'm just saying I'd rather not experiment with Cáceres right now, since he's improving on that RB position and doing alright, mainly going forward. Grygera doesn't offer that so much.
It's like fixing one position and making the next our main problem, and we don't even know if that fix will work. Him and Chiellini make a strong and pretty fast duo, but I think I'd be scared with those 2 CBs right now..