i'm sure we all use something from inside that connects us to the poem, but that encouragement to write from different viewpoints helps broaden our perceptual horizons *nods*. it also helps build empathy and understanding by encouraging us to recognise how others view this world we share in very different ways. gets us beyond our own id's parameters.
for me, it's not an uncommon experience to dream as within a different person, no limits to gender or age; sometimes i'm 'that person' mentally, sometimes i'm me but in their body looking out, sometimes i'm a passenger (sometimes the one in charge, sometimes in the back of their brain, experiencing what they are but not instructing/directing). that spills over into my waking world and often have been thought to be sat on a fence when, really, i am looking at both/all sides of an issue to try and best understand it. that seems to naturally fit in with writing as i can slip into different skins (the poems' skins) and write as their voice, tethered, though, in most cases by that connection to my own id.