Quite honestly, though I'm a big Redfly supporter, I wonder about the utility of this viewer as anything more than a 'proof of concept'
OK I don't think it really has great value for most of us, but here's three use cases that I have for it
1 - conference presentation. I'm a eLearning developer. I have a interest in mobile learning I demo stuff publicly a few times a year. Mobile Viewer is one way I can access my phone and show it alongside my main presentation instead of swapping devices.
2 - If I worked in an office, I could easily monitor my phone messages etc from PC, maybe use my phone for personal browsing if IT is tight. Of course I have to convince IT to let me install the Mobile Viewer software ... but I work from home and don't actually care about this
3 - a company with mobile workers who use their phones for everything, maybe use RedFly on the road, might want to deploy Mobile Viewer to make for easier access to phone data while the mobile worker is in the office/at home because a full PC screen/keyboard is more usable.
I think you are right that most of us will never care about the Mobile Viewer, especially at the $40 price point. But then most people have no use for a Redfly either ...
Put a different way, I think Mobile Viewer can solve the needs of a niche market, but most of us are not part of that niche