Looking at pictures when trying to read is absurdly distracting, I wouldn’t recommend just taking pictures. Instead, you can use a tool to convert a photo into a pdf document. It rips the text from the photo and types it for you. That enables you to just upload the text, which makes for a much smaller file size while having higher quality for the things that matter. But it’s still very involved, you will definitely want to proofread the entire PDF to ensure it didn’t make any errors.
Unlike that other guy, I think the less valuable a book is the more it needs to be digitized. An incredibly valuable book will be stored in a museum, and will likely be digitized if it needs to be and is capable of being. Whereas there are millions of books that don’t get many copies and no one thinks to digitize them because they’re not “important”. That results in immeasurable amounts of lost media. Plus, if the book is cheap, then there shouldn’t be any issue getting a second copy just to tear off the spine and scan it in, right?
Also worth noting, if the book is valuable and you do tear off the spine, there are a ton of places you can send the papers to and they’ll make you a custom spine for the book and rebind it for you.
To your last statement, the answer is always yes lol. Admittedly, without despining it your going to have difficulties scanning in the text closest to the middle of the book, but any knowledge or media being archived is amazing.