For example, for non-removable, typically mobile, soldered-in hardware. You don't buy it because its nvidia, but because its whatever else it is. Sometimes it isn't even disclosed that its crippled by nvidia hardware. In cases like this, I think they owe source code if only as a matter of respect.
For discrete hardware however, its hard to argue that they owe anything, because you pick that hardware by choice.
For software such as opera browser, I couldn't care less. Its always been a completely crappy browser, and there are plenty of alternatives, that actually ARE open source.
Where it becomes an interesting argument is in situations of [near-]monopoly. When there isn't an alternative, and its being rammed down your throat by force.