If you're unhappy with the selection, I suggest you talk to the library system. If you don't want to talk to a librarian at your local branch, check for a website where you can submit comments. Or ask the librarian where you can send those sorts of comments. Often libraries just don't know there's a desire in the community for a certain topic of books unless someone starts asking for them.
One other note, since Dragonfaerie's comment reminded me to comment on the library stuff. (Librarian, though not a public librarian.)
- Even if a book isn't in your own library, your library may be able to get it from another library through interlibrary loan. (This has some restrictions - you don't get to renew the books, often, for example) and in some places there's a small charge to help cover mailing costs (other places it's free, and when there's a charge, it's often a token $1-3 to make sure people actually get them and use them.)
- Many Pagan books, for complicated reasons, don't get reviewed very often in the common professional review journals that libraries use for the vast majority of their orders. (The really really big ones do - but it's maybe 2-3 titles a year for everything in the Pagan realm.)
- Books are even less likely to show up there if they come from a small press (like Immanion, or any number of others out there in the Pagan world.)
- Many libraries are under extreme budget pressure, and are also (in part because of this) centralising their ordering in one place, with items sent to different libraries in the system. Sometimes a particular branch will have a specific focus (like books in a specific language to a particular place), but 'Paganism' is pretty diffuse in most areas.
- So, the best way to indicate interest in a specific topic or a particular title is to request it. (The librarians have access to any reviews that were in the professional journals, but if you happen to know of a really clear, professionally-styled review that goes into details about content, they often have somewhere to include that.) Libraries do have some discretionary funds for their own specific users generally.
- As already said, Pagan books are one of the types of books most often removed from and not-returned to libraries. (Stats I've seen in several places as well as librarian anecdotes suggests that it's at least as much Pagans checking them out and keeping them as people who disapprove of the religion.) This makes libraries a little wary of spending money on them over and over again, but means that if you can suggest titles that go beyond spells and other topics that tend to be more popular to steal, they're more likely to consider them.
- For people who really want to encourage the library to consider a wider range of Pagan titles, see about having a Pagan group sponsor a small collection of titles, provide a suggested book list, or other things that will help the library serve the community. (And, actually, now that the Hennepin and Minneapolis libraries are on the very tail end of a massive 3 year combination project, I might bring this up locally again.)