It's not that powers of 2 are more important. It's that there will never be, for example, a RAM chip that has 32GB of RAM. They will have 34.36GB, which is an ugly number. But, they happen to have a very nice, round number of bytes if you look at them otherwise - they have 32GiB. And since these two numbers are pretty close, and the clean power of two one is far more natural for humans than the SI one in this context, it was natural to just call it GB.
Does that hold up in practice though? Last I checked my USB drives and RAM bytes were not perfect powers of 2. One clear example that comes to mind is my GPU with approximately 12 GB of RAM. That's no power of 2.
These numbers being a power of two seems pretty important, important enough that we redefine words to match powers of 2. Then, when we look at the exact number of bytes, it's not a power of 2.
The important point is that they are multiples of powers of two, instead of multiples of powers of ten. Your RAM has 12GiB of RAM, but in SI GB it has 12.884 GB of RAM.
Flash gets fussier especially when there are reserved sections.
But come on, are you really saying that 1100 0000000000 0000000000 0000000000 bytes of RAM isn't close enough to being a power of two to prove the same point?
Our starting point is that a kilobyte is 1000 bytes, but then people say "that's not close enough to 1024, which is a power of 2", and so we redefine the word "kilobyte" to mean 1024, etc. Then I buy a device with a gigabyte and it doesn't have 1,000,000,000 bytes, and it doesn't have exactly 1,073,741,824 (2^30) bytes either, it has some other random number.
So we started with Système International units and a common understanding of what they mean. Computer people said, "that's not close enough, let's redefine standardized words so they will be exact", and then they use those redefined words in an inexact way.
And for the sane normie people, a kilobyte is still 1000 bytes.
But no, being a few percent off is very different from saying "it's not a pure factor of two, it's a very small number multiplied by a very large power of two".
Your GPU has an exact multiple of 2^30 bytes of memory.
If you want to talk about a USB drive, then to do that properly we need the size and count of chips inside a real model.
