Re: 128GB minimum?
Just as with spinning hard drives there's a minimum efficient size due to the overhead - controller, DDR cache, SLC NAND cache, assembly, test, along with a certain contribution needed to cover fixed costs like R&D to develop the product line, marketing, etc.
You may only need 32 GB (and certainly aren't typical in that regard) but you're not going to see drives that small anymore. So long as they keep doubling the number of bits they can store every couple years, the minimum efficient size for a drive will double. By 2020 you might have to buy 1 TB drives to store your 32 GB. The good news those 1 TB drives would cost the same as a 128 GB drive does now, or the 32 GB drive you bought a few years ago.