Actually WiFi does not make better sense. It is slower that direct connect. And just because an app is provided by one company (Comcast) versus Verizon Fios means nothing. People are just not going to jump from Verizon because of a Roku app.
They are going to bring teasers to customers to attract business and most will see that because of a gimmicks the companies will lose customers based on prices rising and not because of a app.