NO cell phone manufacturer should EVER tie themselves down to one service provider.
Each provider has markets where it is strong/dominant, and other markets where it is weak. One city will have great Sprint coverage, another great AT&T coverage, and a third place may be good only if you have Verizon Wireless.
In my region, I would never have AT&T. Sure, it works in many areas, but the dead spots are in areas I use. Verizon, on the other hand, comes in clear as a bell.
Note that I have not mentioned customer service at all. This also varies by company. When I tried to switch from Verizon Wireless to Sprint and my monthly bill would have gone down significantly (by about $50), they denied me. My credit at the time would only permit for 2 lines and I needed to add a line for my mother to my and my wife's plan. I asked to talk with someone who could make an exception, but they said no one could override the computer's decision.
I called Verizon Wireless, and they said they could reduce the cost of my plan and add a third line, but they just needed to get a supervisor's approval. I called the 800 line, and it only took about 5 minutes to have my mother's phone shipped.
Of course, since we don't have any laws to protect the consumer, service providers in the USA merely blacklist those who try to make the same phone for each company and thus take away our choice by requiring provider-phone hookups. So, in the end, I guess it is better that Apple admit defeat and succumb to AT&T's will rather than be drived entirely out of the market place.