Why would you post an article with drive sizes in English measurements and dimensions in Metric?
Because drive form factors, like wheel sizes on cars, were standardized in inches way back in the day, and conversion doesn't get you even millimeters. Would the article have been improved somehow by specifying the number of 88.9 mm and 63.5 mm bays instead? When writing, you want the most people to be able to understand, and people understand when you talk about drive sizes in inches, even in metric countries. If it bugs you that much, commit those numbers to memory, along with 133.35 mm for 5.25" drives.