With SANS, the iops budget is a function of your hardware config. If you want more IOPS, you get more RAM/SSD involved. More importantly, Amazon gets to sell EB

With SANS, the iops budget is a function of your hardware config. If you want more IOPS, you get more RAM/SSD involved. More importantly, Amazon gets to sell EBS on their terms: a specific amount of IOPS with a specific amount of storage. If you want more IOPS, you have to buy more EBS. The "wasted storage" you're thinking of would be on your instance using EBS, not EBS itself.