From what I've read (not in any definitive military source), the ranks of brigadier & brigadier general were introduced more-or-less simultaneously: the Americans & French having the latter while the British used the former. Of course, the CF changed the rank when they unified in the '60s to match up with the international ranking system (or whatever that thing is called with E-1-n for NCMs & O-1-n for officers).
From my own mostly-uninformed opinion, I'd rather have the x-general ranks for certain staff appointments only: like the CDS ('Captain-general of the CF'?) & the CFCWO ('Adjutant-general of the CF'?). Then leave the ranks of brig, col, etc. for officers commanding various commands, formations, bases, or what-have-you.
I know that the navy used to don the title 'commodore' to any officer in charge of a flotilla of ships (I believe a squadron was reserved for admirals). We midshipmen, however, abused that title when put in charge of several very small boats. So the admiralty changed the appointment to be for captains only.