If I buy an iPhone 5 from ATT and unlock it, even if I pay for a Straight Talk SIM and use that from time to time, I'm still on the hook to pay AT&T whatever monthly fee the contract obligates me to pay.

The only reason AT&T would want me to not unlock my phone, is to ensure they have a captive market for further services that are not part of the contract. Be they usage overages, international roaming, etc.

They'd like my $70/mo for a base smartphone package (with an absurd early termination fee to boot) and to not have to compete for any additional or international service I may need.

Now you can certainly argue that that's a consideration people are willingly agreeing to when they agree to buy subsidized phones on contract. But the argument is that it's a consideration that ought to be explicitly spelled out in the contract terms, rather than enforced by an end-run through copyright law that most people don't know about and have no reason to believe holds any bearing over how they use a device they're paying for.

Also, the contract doesn't say anything about (un)locking the phone. An unaccountable executive reading of a largely-obscure copyright law is the only thing saying it. And it isn't being termed a violation of the contract, it's being termed a violation of the law.

The fact that the 'lock' consideration and implications aren't explicitly in the contract is rather the point.

Is it that since I think the situation is wrong that I must necessarily think the party that currently stands to benefit is necessarily evil or shafting the other side?

Or is it simply that: because I disagree with you, you assume I hold every position you also disagree with?

I'm sorry, but either of those is simply wrong.

My objection is that an appointed executive can so massively alter the effective terms of private contracts without those terms, or even the law's relevance, ever being reflected in those contracts.

If the 'lock' term was in the contract, I'd be fine with it. I think many people are, in fact, well served by subsidized phones, even when/if they come with 'carrier lock' provisions.

As a minor related concern, I think the situation is worthy of perhaps more-zealous scrutiny, because of the effective duopoly.

Given these terms aren't in the contracts, along with the duopoly's refusal to offer a "byo" phone plan with prices (and early termination fees) that reflect the lack of any subsidy that needs to be recovered, the expected and observed effect is a large distortion in the market toward subsidized phones.

Again, not because I think no-one should buy subsidized phones or they're some sort of 'rip-off', but because I think it's wrong and anti-competitive for the market to warp the cost-benefit of subsidized vs byo.

And having to pay for a subsidy you're not receiving is a very large distortion. Particularly in those places in the US where alternate carriers don't have viable coverage.

Though I'm hopeful the Straight Talk/Walmart partnership bears fruit and begets a trend, so that whole part becomes moot.