Even storage mediums that don't employ a power-of-two block size internally, will often carry power-of-two payloads for the user, because to be useful, the stored data will have to be loaded into a RAM chip at some point, and there it will once again find its natural relation with power of twos (it's not like you can't have a non-power-of-two block size, but you would incur at runtime into a waste of storage space and/or impaired performance, and end up working with non-natural units as a bonus).
I agree with you in the fact that nowadays end users no longer care about the exact block count of their devices (why, on the PC everyone was happy calling the 1.4 MiB floppies as "1.44", and the difference was noteworthy back then!) so perhaps OSes should employ power-of-ten units for user-friendly displays. Plus, that would match the units used for network transfer, which historically have never been based on power of twos. Then again, you should also say in the case of lumber "7.62 cm by 10.16 cm" instead of "three-by-four", as inches are asinine units and have no natural relation with physics