or to rephrase, If your application a valuable is a labor saving or time saving advancement, what is the best model to make sure you can benefit the most from that?
How do you effectively distribute that advancement so that it "rises the tide"? Is a price a valid indicator of value? No, we see these days that free services are much more quickly adopted. Most people judge value by practicality and word of mouth.
If you start extracting value from that service by charging for it, aren't you effectively negating the benefit to society?
Imagine you invented a murder App. (lets call it iMurder) This app replaced the need to murder people, through a complex spanning tree alogirthm that combines social network data and communication and travel restriction protocols (commonly known as SAML) and a fully immersive augmented reality overlay. (compatible with Google Glass)
How much do you charge for this app?