I, too, would prefer having the whole caliber rather than just a fraction of it.
Guns have been around for awhile, and we seem to have accumulated multiple naming conventions over time. Slang truncations change and units change. The very word "caliber" is a corruption of the word "caliper", referring to the instrument used to measure the diameter across a bore or groove. Only metric cartridge names are expressed consistently and specifically in millimeters, though even they toss a few hundredths of a millimeter around here and there to distinguish a name or because the commercial diameters have changed over time, allowing history to erase the literal value of the name. The metric names pretty consistently refer to bore diameter and case length, not bullet or groove diameter and case length. So it's really the chambering name the cartridges are labeled with.
We and the Brits like to confuse things more. Many of our rounds are named for bullet or groove diameter rather than bore diameter, but we do both, and on occasion use the approximate case diameter. 38 Special comes to mind, where the bullet is closer to 36 caliber and the bore almost exactly 35 caliber). Using the singular "caliber" when it should be pluralized with an s on the end is another convention that's stuck with us over time. Sometimes we speak in inches by asserting the decimal place, while at others we speak in thousandths of an inch. An example would be saying: "Three Hundred RUM"; that's three hundred of those little thousandths. Nobody would say "Point Three RUM" or "Thirty RUM". The manufacturers go a step further with labels that include trailing zero's that ask for that pronunciation in thousandths and, again by convention, we take that to imply we should not mention the decimal place, "Point Three Hundred" would be an egregious misuse of thousandths. But labels still sometimes put it there and sometimes don't.
Confusing enough? It's old language refusing to settle on a standard. If I had my druthers, we'd just go metric to avoid confusion with the artillery term "caliber", meaning the number of shell diameters the length of the barrel is, regardless of shell diameter. We'd be upset for awhile, but all the digital calipers and micrometers have in/mm switches on them now, so I think we'd get a handle on it pretty fast. We reload plenty of metric named stuff now, and the full metric name convention would avoid the situation where someone walks into Rocky's gun store and asks for some "7 mm bullets" when they really want a box of some specific 7 mm cartridges for a specific 7 mm chambering.
