Because the only channels you will receive over the air is the local channels that are located in your general area. What do you want a bunch of broadcasting towers with the hidden costs of maintenance, or a bunch of copper (most likely) cables that do loose the signal strength with distance? I am not sure if television companies support fiber optics signal.
Imagine your TV being similar to your smartphone, only now the television companies charging you with data caps, and, they dislike you for using their broadcasting towers because users are killing their bandwidth, and they are going to recommend to use your WiFi to stream your channels to save data. The really best part of it is that your TV is going to be sold by the cable companies and locked by the companies accordingly.