So even though Crowley doesn’t read, he still gets that Aziraphale loves books - really gets it, simply because books are important to Aziraphale.
Compare that to the attitude expressed by the other angels. In the unfilmed Regency scene, Gabriel didn’t consider that Aziraphale could have an attachment to his bookshop. Crowley showed up with chocolates because he knew how special opening the bookshop was to Aziraphale and wanted to celebrate it.
The other angels are dismissive of human propecies. Gabriel classifies books as just “material objects,” tossing them aside casually. But Crowley saved Aziraphale’s books. He thought of saving them even before Aziraphale did! Just because he knew Aziraphale loved them.
Before Crowley left the burning bookshop, he grabbed the copy of Agnes Nutter’s prophecies. Remember, at this point he didn’t know what the significance of that book was. He must have grabbed it simply because it hadn’t been burned up - because it was the last piece of Aziraphale’s shop - and Aziraphale - left. I mean, he brought the book into the pub with him while he was drinking and crying over losing Aziraphale.
Another thing that kills me is how soft Crowley’s voice was both times he told Aziraphale that his bookshop had burned down. The first time in the pub he tearfully said “I’m really sorry” and let Aziraphale have a moment to process it, knowing that it would hurt Aziraphale to hear that news. And when they’re sitting together on the bench waiting for the bus, Crowley seems to hesitate when reminding Aziraphale about it.
During the body swap, Crowley went into the restored bookshop to check on things, gently touching the books that he’d seen burn. He even knew enough about Aziraphale’s stock that he was able to instantly clock the new books.
Maybe it’s the bibliophile in me, but Crowley’s validation and support of Aziraphale’s love of books just… really gets to me.