some TVs came with cameras, for gesture based remote control.

yes, it was found that the cameras were abused.

or what if the malware took screenshots of what you were watching every so often? oh wait, that was also found to be a built-in "feature".

otherwise, they are a foothold onto the rest of your internal LAN, possibly with other more vital IoT devices ready to be compromised, or at least serve as a botnet army