I'm also a member of the 'We Probably Have Enough Books' club. At this point I grit my teeth any time the meme pops up.
And for me, the frustration stems less from how many actions we have spent on books and more from the fact that it feels like any time we get a reward for completing a quest or story arc, people jump out of the woodwork to insist that we find some way to synthesize it into books we can toss into the Book Nexus, and we (myself included) have to spend time shouting (posting?) down that option so a meaningful boon we can use to change the world of the quest in a vastly more interesting way doesn't get blown on Dewey Decimal Number Go Up.
It's also vast understatement to say we don't choose it too often when the fucking Karak Eight Peaks Transcendental Boon (which we got for, among other things, engineering the death of an entire Waaagh and otherwise basically reversing the karmic momentum of the dwarven race) got used on building a library which we occasionally Make Number Go Up in.
I have to CBT myself away from reminding myself of that too often because I frankly get too upset - like, do you understand that we could have asked Belegar something on the level of 'helping secure a lasting human principality in the Borderlands'? It wouldn't have done it by itself and probably prompted a campaign to fully actualize, but still. It could have been used as a solid chunk towards literally redrawing the map.
But no. BOOK, amirite guys? Yuk yuk yuk.