First I should note that efuses also exist in more classical fuse functions, indeed that was their original purpose, and will isolate components when they fail or are not necessary for the operation and you can save a bit more power/generate less heat by wholesale removing it from the circuit. Similarly they also exist in identification functions (think burning a serial number) and while I don't know that I have seen it yet then batching as well (think all those nice software locked tools, oscilloscopes probably being a good jumping off point). Going back in history I would also look to the likes of write once memory, though I suppose it was born of a technical limitation more than a design requirement. Going back into nuts and bolts engineering then there are plenty of one time fasteners, ones mechanically designed to be so and for no other reason, and they go back a very long way.
Because Congress (technical illiterates for the most part) hasn't passed any laws against it. Things don't just become illegal, there has to be a law passed to do so, (or some activist judge acting outside of his legal authority under the constitution)
I would argue otherwise. There are held to be fundamental principles/tenets of law making and things you are allowed to do, or indeed not allowed to prevent others from doing. While theoretically most of those could be changed the political will is likely never going to be there to do that (and if it somehow is then something has gone very wrong). Said tenets can be fairly abstract so if you are arguing a case and can point at a more specific law then it is quite useful to do so.
Similarly while I am sure there are and have been judges that seek out things and attempt to do things, or indeed run places, then you may risk confusing the actual role of judges (which is to interpret the laws and weigh them against said fundamental principles, and possibly other rulings, aka case law, depending upon the system you are under).
Returning to the history thing from the opening paragraph then suicide/self destruct/tamper lockdown type things have existed for a great many years. 1989 being when Capcom did the whole suicide battery thing
http://www.arcadecollecting.com/dead/ . Since that time we have had probably most of the fundamental rulings on tech outside of the very first software vs hardware stuff in the 50s and 60s.
With all that said I am not sure I see a path to making efuses as a one time DRM measure unlawful in and of themselves. Nintendo supposedly has a try hacky then no worky option in there and that might see more scrutiny than the 360 equivalent wherein you just get to flash the relevant NAND image back again and it all starts working.
If there is a path I imagine it would come more from right to repair* (which software locks can make unfeasible even if the hardware aspect is trivial) or environmental concerns (see various rulings in Europe for unlocking routers or mobile phones), and then the obvious counter move would be "well you can't replace these batteries because look at this fire", "we made it waterproof" or "look at this heat conducting epoxy".
*a concept right now which is on fairly shaky ground.
Maybe there would be a route along the lines of you sold be a non functional device/device which does not comply with stated functions, however "we ship the necessary updates on the disc/cart" would stop that fairly soon. The cases that resulted from Sony's removal of otherOS being where I might look here. You might have some kind of right to run homebrew but that says nothing about them having to give you or it continue to work with it in their operating setup.
The idea that they are damaging your device is almost a complete non starter from where I sit.
