alt Hacker NewsSince everything ultimately ends up inside a base-2 computer across base-2 bus that even if these media aren't subject to the same considerations it still makes sense to measure them that way.
The choice would be effectively arbitrary, the number of actual bits or bytes is the same regardless of the multiplier that you use. But since it's for a computer, it makes sense to use units that are comparable (e.g. RAM and HD).
Buses and networking fit best with base 10 bits (not bytes) per second for reasons that are hopefully obvious. But I agree with you that everything else naturally lends itself to base 2.