If I bought a computer, I would expect to be able to utilize all the functionality of that computer. Why are phones different?
Many phones have GPS receivers built in. Many of these are disabled by the carriers. You may re-enable the receivers by paying a monthly fee to the carrier. That is wrong.
The same is true for applications. Many carriers only allow applications that have been signed by them to be installed on my phone. This practice allows the carrier to charge the application developer a signing fee.
Both of these practices put the brakes on innovation in the US Mobile market.