Droid X - phone or pc?

I find it curious that the new Motorola Droid X, a follow-up to the popular Droid ('Milestone' in the UK) phone that really took on the iPhone in terms of sales has a new security feature.
If the phone detects that its ROM has been tampered with it will brick itself, rendering it useless. It uses an electronic fuse, dubbed an 'eFuse', to check that the software has not been touched prior to booting. If it has been, it will lock out and no doubt require a pricey return to the manufacturer.

Custom ROMs are increasingly popular amongst users as they often add functionality and upgrades to devices which might otherwise be locked down by the phone's operating system. As an example, I added a custom ROM to my HTC phone that unlocked geotagging in photos amongst other features.

My main question raised by this is the legality of this move by Motorola, either moral or judicial, as it brings us to wonder whether the phone is now a pc or still just a phone? No one would accept not being able to hack and customise their computer but Motorola expects that users should accept the curtailing of this option on their phone. It is skewed further when you consider that Android, its operating system, is open-source! Surely the whole idea behind using Linux on a phone is to allow this customisation process to happen?

Modern mobile phones offer all the apps and features of a modern pc but this move to limit user tweaking seems odd. Anyone who tinkers with their phone knows the risks but surely we deserve the right to do so? It will be interesting to see if it hurts sales of the device as well.