And yet, my players have no interest in this at all. So I don't know that it is "important".....
And this is why its such a good candidate for a crunch heavy, "optional" book. Its a crunchy addition, and as you said certainly not something that everyone would need, so adding it doesn't "impose" anything on other players.
Now of course, polls will determine how "important" this is to the fanbase, but it is a solid solution to the gold problem.