I've never got into HDMI-CEC since I've always had a Logitech Harmony remote (I've also had a complex setup of multiple things so getting them all on/off as needed wasn't so simple).
I've just checked and for a $198 TV I'm a little surprised that it does HDMI-CEC (although maybe it's just standard with everything these days). That said, when I tried to turn that on on the ATV it said something like "not available in this configuration".
In reality, I'm using the TV remote to control the ATV at the moment, so while I don't get all the touchy voice stuff unless I reach for the other remote, I haven't needed/missed it yet.
For reference, this is my cheap bedroom TV:
On a side note, I'm using an alternative iTunes account which is registered in the US store (which I needed back in the day to get Hulu and Netflix and MrMC) but now I wouldn't mind installing ABC iView and the other catch up services but even though I've changed the region I still seem to be in the US store... am I missing how to change the store in the ATV4??
Update: I don't know if I need a "better" HDMI cable, but when I try to enable the turn off my TV function I get a warning saying "Can't use system control with this configuration"