Ugh, that seems like it just exchanges one form of waste for another. If it takes off the price of storage is likely to rocket in the same way GPUs have.

Let's not shoot ourselves in the foot, again, for another digital gold rush?

IIRC some Proof of Storage algorithms allow you to store actually useful data, and there shouldn't be any incentive to get fast storage, so it should have less of an effect on the average person.

True, and I understand this is how projects like Sia work. But IIRC Bram Cohen's proposal was effectively PoW but with storage.