I agree. While loving to read is nice, it shouldn't be the main motivation to be a librarian. I think that what you have listed for the realistic motivations are more relevant for the type of work most librarians do (I lean more towards the organizing and retrieval reason).
I can only think of another bad reason to become a librarian: because it's "hip". For the record I really don't care if being a librarian is "hip" or not since I place more value on *what* a librarian does and not what social status being a librarian gives you. Nonetheless, if it's the main reason why someone's becoming a librarian, then they need to rethink where they're going in life.