If anyone has ever looked for Imperial Guard mini's on eBay or other places you'll understand the difficulties when most of your results are some Napoleonic stuff.
That is an excellent point that didn't come to my mind, actually.
It isn't like this is the first Codex to get it's name changed, after all. Adepta Soroitas used to be Witch Hunters and Sisters of Battle (the didn't use ), Grey Nights used to be Deamon Hunters. This is different in that it's an unknown phrase.
Though that's a bit different as the "... Hunter" codices were not just Battle Sisters and Grey Knights, but also Inquisitors and their retinue. The books had an overlapping, somewhat uniform Inquisition-focused theme, and the SoB in particular were only temporarily thrown into it to give the Ordo Hereticus Marine-level troops.
A third book called "Codex: Alien Hunters" featuring the Ordo Xenos and the Deathwatch was planned (mentioned in the WD Designer Notes) but ultimately never saw the light of day, and as we know the focus of the Sisterhood has reverted back to their Ecclesiarchal duties with the 5E White Dwarf Minidex.
There is the theory that the temporary Inquisitorial focus was solely the result of GW's own d100 "Inquisitor" project (the origin of the Deathwatch, originally conceived by GW as a way to deploy Space Marines alongside human characters).