Probably restating the obvious, but this is after all essentially not so different from CPU vendors fusing off cores, or GPU makers fusing off bits of GPU, stream processors, video encoders and decoders, what have you. I think you used to be able to flash back the missing features with a different video BIOS(Don't try this anymore), or with luck restore a Phenom X3 to X4 in not so distant past.
tl;dr Fusing off perfectly good silicon for product segmentation is not new, even though slightly more unpalatable for RAM, which you could never have enough, unlike CPU and GPU cores, especially when there's only 8GB to start with.
Now what would be infuriating and maybe anti-consumer is if they would offer to unlock that extra 4GB for a payment at some point, like some car makers would offer to "unlock" heated seats for a payment, with hardware that's already physically present in a car physically bought, weight penalty and all.