Let me answer these by saying...why do you need to spend money on an aftermarket stereo? Isn't the one that comes with your car good enough?
My point is, there's something that we find technically challenging and interesting to do...not because it's a necessity, but because there's something about it that's cool. Personally, I find the concept of being able to talk with someone thousands of miles away using nothing but my own stuff and knowledge to operate it interesting...sure, you could just call someone up with a cell phone, but that's not the point.
Most of the time, amateur radio is simply a hobby, whether you're shooting the shit with the locals or talking with someone halfway around the world, but there are other times it can come in handy for emergencies...after all, if you think your cell phone is worth something when the shit hits the fan, I can only //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif at you. Cell phones are very useful devices, but I find people's reliance on them to be funny and dangerous...for other uses of ham radio, SKYWARN weather spotters often are the "eyes and ears" of the local weather agencies during bad weather. The local club here has also ran tactical communcations for 10K races, fairs, and other large public events where a network of skilled communicators is needed...I guess we're important enough to the Red Cross for them to use amateur radio to pass health and welfare traffic out of affected areas (last year's hurricane season in FL being a great example).
Not to mention, you can learn a lot about the technology people use to communicate - after all, amateur radio has already been where the public is just getting to. Cell phones? Based off 1940's narrow-band FM repeater technology. On-Star and other GPS location technologies? Hams were messing around with packet radio position reporting systems years before it went mainstream.
CB - well, that's like your vulgar friend that provides some entertainment from time to time, but you wouldn't want to invite him over in your house //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif I use CB on the highway for finding out where the cops are, and to listen to some redneck banter, but that's it //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif