Many "popular" things are the ones being taught. If you listen for a period of time in advance, you get the aircraft type as part of the initial call, at least in the current RT procedures.
If you feel it will support enhanced safety, just call out type and others may feel the same. In a busy situation I do occasionally. And yes, I support the country call-out. If there is a D-, N-, OY- in front of me in a UK traffic pattern, I switch to enhanced surveillance, because I assume enhanced unfamiliarity with the local peculiarities. Further yes, there are situations at busy aircraft flow, where the type is more helpful, such as I experienced in the pearl chain to KOSH.