I don't follow the custom Android distro or handset hacking worlds very closely, and once you've rooted and flashed a custom distro like the excellent CyanogenMod on your phone you've wrested back about as much control over your own hardware as most people need, so I only just noticed that the HTC Desire's NAND protection (a.k.a. the @secuflag or S-ON) got beaten by the AlphaRev team a while back. Even though I don't fully understand the implications, this makes me happy; any increase in the control customers have over the devices they paid for is great. I had a quick FWSE but couldn't find any substantial discussion of the practice of locking down the hardware (I guess it could be termed weak Tivoisation?). Paul @ MoDaCo said "Shame on you HTC for going to such unnecessary lengths (but that's another story for another day)." Cory Doctorow said "what a misery it is that the mobile phone companies continue to spend good money to frustrate the legitimate activities of their customers". Also, HTC clearly has a cynical view of the GPL, following it in letter but not in spirit.
The ability to unlock/root/whatever was a significant factor in my choice of smartphone. Back in July '10 when I was choosing a smartphone I shortlisted the Desire and the Motorola Droid 2; the Desire was already rooted, but I would almost certainly have held out for a Motorola Droid 2 if they'd said it would be rootable. Instead they said they had no intention (I'm sure I remember a much less friendly statement of refusal from Motorola but I can't find it now). At least they were open about it! Several months on I'm very happy with the Desire, so perhaps it's for the best. The Droid 2 turned out to be rootable, as did the T-Mobile HTC G2 more recently. I really can't tell whether we should worry about the future. All handset manufacturers could go the TiVo route if they wanted to, so it seems current devices are only rootable because they want to make it difficult/risky, but not impossible.
Handset manufacturers are driven by profits, so there must be an advantage to the manufacturer in doing this (or a disadvantage in not doing it). Hackers like the CyanogenMod team will bring out the best in a handset and a tiny minority of early adopters and geeks will test it out; the manufacturer gets protection against having to honour warranty returns if we brick our phones in the process, plus free testing/stabilisation of features they can consider (and indeed copy) for later stock firmware releases and future phones. They also get "plausible deniability" -- they can claim to networks that they've done their best to hand control to networks over features like wireless tethering and removal of garbage bundled apps, which networks don't want end-users to be able to do (higher support burden, less income from "value-added" services they've bundled, more load on the data network). I guess it also frustrates attempts by competitors to copy whatever innovative features the handset has, but my understanding is that competitors are more than capable of completely reverse-engineering a phone, and that preventative measures have a negligible effect.
When I buy the unbranded version of a phone I expect to pay more and I expect full control in return. Sadly those of us who expect that are a tiny minority of the market and have almost no sway. Increasingly, I recognise this as the trade-off you get for living in a free society. Shareholders want the maximum return on investment, at any moral cost. If there's a morally indefensible but slightly less expensive way to do something, that's how it'll get done -- capitalism rewards greed above all else. In a sense, though, it's Rawls' "First Principle of Justice", so I guess I'm at least free to be just as morally obnoxious.