To this day, I believe that it's still the primary reason. You hope that the person has a screen presence and can actually talk too of course. As an example, I'll tell you that when Erin Andrews started out, her first big gig was doing Atlanta Braves broadcasts on TBS. She was in a studio, a single desk/chair setup and all she had to do was give updates on other games around the league and the current game we were watching. She was terrible. She couldn't say anyone's name properly and honestly looked petrified doing it. They stuck by her and gave her a chance to work things out. Over time she refined her skills and look at where she is now; she's hosting a College Football show on Fox and doing sideline reporting additionally.
In positions like this, all that you can ask is that the person doesn't embarrass themselves or the company that hired them first and foremost because of their looks. The host or entertainer must take it upon themselves to make the most out the situation. Chobot looks like she doing exactly that.