This question is sort-of spun off of a previous one.
There are a lot of great security-focused answers there. However, I think the true question that is brought up is more about privacy and anonymity than it is just security.
I'm looking for concrete examples that can be presented that show the need for strong security when conducting perfectly legitimate activities. Examples in the areas of trust worthy encryption on end-to-end communications for cellular networks, network identity obfuscation services like Tor or VPNs, complete and total data destruction, and so on are what I'm after.
I'm always inclined to point to social uprisings in states like Libya and Egypt but these events tend to be presented to too many of the people I encounter that use this argument as "things that happen on TV" and not real things that have any effect on them or their personal liberties. So counter-arguments that keep it squarely in the first world, it-could-hurt-you-or-your-grandma kind of are really valuable here.
The examples brought up in the post copied above are really more specific to privacy and anonymity than they are about general security. I'm sure you'll find that most "Joe Users" will agree there is a need for Antivirus, Wi-Fi encryption, and other common defensive measures. But, why would the same people have a need for things like Tor, or end-to-end encryption over cellular networks?
To be a bit more clear: What are some arguments for personal online privacy/anonymity that your regular Joe User - who plays Angry Birds on Facebook while sitting in his boxers on the living room couch - will relate to?