>>51503140Stories that use genderswapping as a way to add extra tension are as old as dirt. Whether or not it's a "trans fantasy" is irrelevant, as it's not something the character willingly chose, and just adds to the turmoil of their situation. You don't need to be trans to entertain the idea of suddently having a different body, and this applies to gender as well.
Whether or not it actually adds to the story really depends on how it's used. A story can use it to play into gender roles and stereotypes, where the person in question could either reject or embrace certain situations. They could be a particularly pretty female, attracting males all the time and starting to question their sexuality. It could simply affect their thinking and reactions/instincts, as hormones are one hell of a drug, if their current bodyswap doesn't already do enough of that. Learning to cope with a changed situation is the bread and butter of bodyswap stories, more changes = more chaos, generally.