Whether or not they are metaphors, there are certain teachings that seem to be catered to different audiences. For example, for some time I was perplexed by the Buddha's statement to Ven. Anuruddha in the Nalakapana Sutta, which seems to suggest a useful metaphorical aspect to rebirth teachings. Regardless of whether rebirth is literal (post-mortem) or metaphorical (moment-to-moment), it is helpful for some to believe in it.