I agree with the fact that Apple shouldn't have bricked it but you have to remember that Apple isn't a company that is going to cater to people trying to fix the companies mistakes. They locked the phone so game over if you don't want to switch to AT&T. There were other options. The users that hacked the phones to use on T-Mobile's network, I assume, were smart enough to know that updating the software would have destroyed the original programing.
We feel the user's pain, but after hacking into the software and breaking the license agreement and voiding the warranty on the phone, the franken-iPhone user should have been more careful with software updates.
McDonalds lost that lawsuit because they didn't put a warning on the cup that the coffee was extremely hot, now they have it all over the dag-on cup along with caution tape and flashing red lights.