I think there is a bigger question to be asked. Should you keep up with technology trends in general? You can obviously live a very fulfilling life without them, but do you risk getting increasingly isolated/marginalized? For example, if more and more people turn to FB (or social networks as a whole) as a communications tool, you will be left out if all you have is e-mail access.
I use facebook a lot to keep in touch with family & friends. We also use it in our neighborhood as a announcement/discussion board. Thanks to BigMoneyJim, I now understand the value of Twitter!
I didn't get GPS thinking that if I mapped out a route before I left home, I wouldnt' need it. Turns out it is really useful. Want a starbucks while traveling? Ask the GPS for the nearest one. Want to avoid traffic - the GPS does it for you. Do you want to know what the speed limit is, the GPS shows it to you. I love it & all for less than $100.
Currently, I'm struggling with whether I should get a smart phone. The cost of the phone isn't the issue, but the $29/mo data plan is. Do I need it? No. But, if I have it, I can participate in communications with my friends who do. It can provide value in daily life too - comparison shopping, looking up information online on the go, having your schedule with you etc., but do I really HAVE to have it? Tough choice for me.
Think of all the people who never learned how to use a computer. How much are they missing out on?