Unlocking your phone has nothing to do with taking advantage of the carrier subsidy. If you are under contract and "unlocked" you are still bound to pay your monthly fee to your carrier unless you pay the ETF or early termination fee.
Whether you buy it locked or unlocked you are being ripped off. They essentially learned it from the US employment/health insurance co-bundle.
Given that several branches have to spend considerable time reviewing just how noncompetitive the wireless industry is, it is kind of absurd for one to hand them another tool to continue competing on everything except price and service.
T-mobile is going to stop offering subsidized phones this year--either pay up front or rent-to-own. Their monthly plans will decrease accordingly, so non-contract customers aren't getting hosed.
If you buy a prepaid phone at full price with no subsidy many carriers have policies on how long you must be a customer of theirs before they give you the unlock code.
Additionally, if you buy a used phone on Ebay/Craigslist - aka nothing to do with carrier subsidies - this now requires you to break the law in order to unlock your phone.
Convinced?
The iPhones, I simply demanded at the Apple store to pay full price (this is before the officially unlocked version was being marketed), and the first time I plugged the phone into iTunes, I got a dialog congratulating me on unlocking my phone. This was not widely reported, but always worked.
The Android phones, I can simply pull out the T-Mobile SIM and put in an AT&T one and I've never talked to anyone about it.
Both types work with pay as you go SIMs in Europe. I've never spoken to AT&T or T-Mobile about any of them.
Convinced?
http://support.t-mobile.com/docs/DOC-1588
AT&T prepaid is much worse:
http://forums.att.com/t5/Prepaid/Unlocking-PrePaid-Phones/td...
"Requirements for prepaid wireless plans with AT&T branded phones: You have had AT&T service for six months or longer You can provide a receipt or other proof of purchase"
The last line illustrates how carriers are dictating policy in an effort to subvert the secondary phone market.
Even more frustrating in the same link you will see that certain AT&T phones are "ineligible" for unlocking presumably due to some arbitrary restriction.