I don't have firsthand knowledge of TVs doing this, but other consumer devices with WiFi most definitely do this. If you don't control the software driving the TV, and the TV has WiFi hardware, I would assume it's at the very least in the cards.

It's rationalized by the vendors as a service to the customer. The mobile app needs to be able to configure the device via the cloud, so increasing the ability for said device to reach cloud by whatever means necessary is a customer benefit.