Considering that everybody plays these melodies from a book, I see no difference in using it in a software. In fact most jazz musicians are making money by playing melodies that do not belong to them. So which is worse, practicing to a software that has the melody within it, or playing a gig and making money with other peoples songs/melodies? I personally think melodies should be an integral part of BIAB. Most people originally purchased band in a box in order to practice over chord changes that were based on songs.