Great feature, but cloud providers are incentivised to make it difficult for people to save money. This would instantly vaporise a big chunk of revenue, because people would not have to pay for pre-provisioned storage.
Edit: Now that I actually read TFA I see it mentions most CSI drivers already provide this functionality. They provide a workaround similar to what I’m sure most people use, and I agree this functionality seems like it could be handled by StatefulSet.
Every business is incentivized this way. Competition is what pushes prices down, of which there is plenty in the cloud industry (though maybe still not as much as we would like).
I guarantee you internally cloud providers over provision their storage.