I have no objections in principle to having the directory naming configurable. However, various caveats apply:
1) It would have to be done in a way that does not break metadata backup/db restore/the cover storage APIs (probably others as well)
2) The default semantics must remain as they are
3) This kind of change will require *a lot* of testing, on multiple platforms, as it has the potential for data loss.
I'm somewhat puzzled by your use case, however. If you are serving up books from a server, what earthly difference does it make where they are stored?