The Book of Catholic Worship

There is a fairly wide-ranging conversation online just now about the early days of post-VCII American Catholic Hymnals.
Someone is seen as "brave" for championing the first GLOP as "not so bad," (not his words, as I recall from skimming the essay in question, but I think that's a fair distillation,) since the little plastic bound hymnal has been much excoriated in the blogosphere, and is short-hand for bad church music of its era as Haagen-Hasz is for our own.
The "not so bad" has two components -- the first is absurd, frankly, since its basic premise is that some of the music is good. I ask, if you set out a buffet for your child every day consisting of vast amounts of Twinkies and Doritos and Klondike bars... oh, and a few celery sticks, and maybe some skinless boneless chicken breast simply prepared... how pleased would you be with your attempts to promote healthy eating? and what confidence would you have in his health after a few decades?
So the assertion may not be false, but it begs a false conclusion.
And the second component of its not-badness is that GLOP was better than its predecessors.
That is where I have my doubts.
IIRC, and I don't care enough to look it up, the writer's opinions of that era in Catholic music are received, as he was not practicing during the timeframe in question.
I have no specific recollection of when GLOP appeared, so I will accept the accuracy of the dates being given (mid '70s,) though if pressed I would have sworn it it was earlier.
When I was in faith formation, I remember singing from them in a certain chapel, but perhaps my memories are of singing from them when attending ceremonies for younger brothers and sisters in Faith Formation. (FF took place at our parish church school and private Catholic schools within the parish boundaries.)
My take on GLOP was that it was for those places without the sense of music, aesthetics or decorum to have the red hard-bound Catholic hymnal our parish had, (not to mention the Latin sung by the choir.)
It wasn't until I was older, attended school out of state, began to go into the city by myself, etc., and participated at Mass in other places that I realized how wide-spread was the, (IMO then, and now,) lesser aid, and how rare, no, non-existent, was the hard-bound.
Well, when our parish went to disposables, my family acquired one of the hardbounds, and it has come in to my possession.
What happened to The Book of Catholic Worship?
I never wondered, really, till now.
It bears a '66 imprimatur and the copyright belonged to "The Liturgical Conference" in D.C., and was distributed by major liturgical publishers (including GIA and WLP, or what I think I recall was the precursor of WLP.)
So, did it have some semi-official status?
And whether it did or not, what became of it?
Oh, I understand, it preceded the promulgation of the new Missal, but why wasn't it up-dated? I'm guessing our parish only kept them around as long as they did for the music, the hymns, since the ordinaries were no longer the correct text.
It was nicely bound (has lasted a long time, with a lot of use;) wonderful paper; has a complete psalter, (albeit not pointed, and without music;) excellent typeface and layout, for readability; a well chosen music selection, especially the hymns and antiphons; beautiful, albeit quickly out of date, orders for sacraments -- virtually no Latin, but it has that in common with GLOP. I wonder if it was expensive; our parish was very wealthy.
So what happened to it?
If it had been the model for what came after it, I suspect the Liturgy would be in much better shape than it is now.
I wonder what, exactly, the "Liturgical Conference" was...