As disk sizes started to increase, the difference started to matter more and more. 1KiB is only 2.4% more than 1KB, but 1TiB is 10% more than 1TB.
I think it makes sense that this didn't become significant until disk sizes started reaching GB levels, and therefore manufacturers' choices to switch to base 10.
Besides it making more difference for bigger disks, there is a huge performance penalty on x86 for disks that use sectors that are not a multiple of 1kiB. And since earlier models were MB sized, they couldn't even get those few percent back.
I think it makes sense that this didn't become significant until disk sizes started reaching GB levels, and therefore manufacturers' choices to switch to base 10.