It kinds of go together, in my opinion.

If something can bring you a lot of joy, by not working it can take that joy away, making you upset. I'm not saying that guy expressed himself correctly, but I can understand why he would be upset at the idea that Apple and Jobs doesn't seem to think this problem is real and needs a fix.

I buy a lot of gadgets, so I'm used to being upset when I realize my $600 toy is not going to be much use to me. But most people do not go through the cycle as often, and they think that buying a product means it's going to work as advertised and not give them problems because they hold it wrong. The fact that the phone loses reception is irrelevant; the disappointment comes in knowing that you have a flawed half-baked product, and that there will never be one that works. Next year, there will be another iPhone, but it will be flawed in some way too. Now Apple isn't as cool as you thought. Now you aren't as cool as you thought. Now the Universe isn't as cool as you thought.

An angry letter seems like a pretty rational response if it means that you can still feel meaning in your life.