The main use case for the disk usage plugin is probably "identify large jobs eating up the disk". Those generally come with quite big numbers, sometimes with gigabytes of disk usage. Displaying all disk usage sizes in kB makes it really hard to see whether some long number like 56234128 is in the range of 5 or of 50 GB.

I'd therefore like to suggest displaying all sizes in MB by default (I don't care of whether it's 1024*1024 or 1000*1000 but rather about changing the default order of magnitude). I'd assume most people don't care about the loss of precision (in the no longer visible last digits), since they want to identify big jobs.

If this is not possible for some reason, then it would be helpful to at least use the thousands grouping separator to format the labels. E.g. in German locale 1 million would be "1.000.000", in English locale it would be "1,000,000" (AFAIK).