Now factor in redundancy and server costs, and the difference is not so huge. You're still paying a multiple of the raw cost, but unless you're storing on the exabyte scale I think it shouldn't really matter in the grand scheme of things.

Cost of a single engineer to manage a Minio cluster probably already outweighs the extra cost you're paying at any reasonable scale (i.e. most companies). And if you're a big player the published costs are not what you're paying.