The dichotomy is not "nice to have" vs. "must have" -- it is whether the threat is "visible" vs. "invisible" when it concerns privacy and security for consumers.

Phone calls being massively scanned by a national security organization are an invisible threat. Consumers don't worry about it.

But consumers will pay for anti-virus software because it's in their face.

Another great example is personal shredders. I remember a skit, perhaps it was on Saturday Night Live, where the kids had to throw dad's incriminating papers into the "family shredder", portrayed as a ridiculous appliance for a family to own.

In the years since we started to hear a lot about identity theft, and then Fellowes created a billion dollar market for personal shredders. Is a personal shredder a "must have"? No way. The risk is very low, and there are so many better ways for thieves to get ID info in bulk. But ID theft is highly visible; you hear about constantly.

While I agree that it is hard sell for the consumer market, if it should somehow became highly visible (like a wikileaks dump of millions of recorded calls as another person suggested here), then sales could fly out the door.

There are certain market segments that privacy and security are a "must have." That may be a relatively small slice when you compare it to something like Facebook, but since Zimmerman is not trying to scale a free service that "small slice" may be significant revenue.

Having said that I do agree that this service won't sell to a wide audience.