Processor architecture

Question

While HDDs evolve and offer more and more space on less room, why are we "sticking with" 32-bit or 64-bit?

Why can't there be a e.g.: 128-bit processor?

(This is not my homework; I'm just a student interested beyond the things they teach us in informatics)

Answer 1

Because the difference between 32-bit and 64-bit is astronomical - it's really the difference between 2³² (a ten-digit number in the billions) and 2⁶⁴ (a twenty-digit number in the squillions :-).

64 bits will be more than enough for decades to come.