Body-swapping is not one of the more commonly used 'flavors' of transformation. Indeed, some even go so far as to argue that a body-swap isn't really a transformation at all. Myself, I think that's a perfectly absurd position. I mean, just try to imagine the reaction you'd get if you tried that line on someone who just woke up in the body of an 8-foot arachnoid, let us say...

Yes, Virginia, body-swapping bloody well is a type of transformation. So why do some people disagree? My guess is, it's probably because these guys have OCD-strength focus on the process of transformation. Show me someone who thinks a good transformation story just isn't complete without a couple of kilowords devoted to "and then Jane felt the end of her spine stretch outside her skin, and then flesh spread over the exposed discs, and then fur sprouted over her shiny new fox-tail", and I'll show you someone who is going to be bitterly disappointed by any story in which the transformation is (from the victim's point of view) pretty much 'Poof!' I'm a [fill in the blank].

Anyway, I think it's a pity that we don't see more body-swap stories. By its very nature, body-swapping is intrinsically binary -- there's two altered people to deal with. Unless the swapped-into body was some sort of artificial construction, specially created for the occasion, which was untenanted before the swap... and even then, an author could say that the freshly-created body had some sort of sentience, even if its creators didn't notice. Anyway: With a body-swap, you've got two transformations for the price of one! Or, alternatively, you get to see how a transformation looks from both ends. For example, both "man into horse" and "horse into man".

Body-swap transformations are extremely well suited for exploring the concept of mind/body dualism. Whatever it is that makes you the unique individual that you are, how much of that stuff resides in your body, and how much is specific to your mind? With other modes of transformation, the victim retains his own body, even if it's been remodeled to whichever degree; with a body-swap, the victim's mind is all he has left! So what, exactly, is in the mind? Would a body-swap victim retain his old memories, or would he only have access to the memories of his current form? One might suppose that a body-swapped pianist would completely lose his piano-playing ability, since that sort of thing is critically dependent on 'muscle memory' and training up the nerve pathways and so on -- but if there's any strictly mental component to that skill, might he not be able to re-acquire it exceptionally fast in his current form?

Those writers who think "and then fur sprouted over her shiny new fox-tail" is the whole point of a transformation will, no doubt, continue to neglect the body-swap in their stories -- and why not? If J. Random TFWriter doesn't happen to enjoy creating body-swap stories, who am I to tell him he's wrong? But for those writers whose concept of transformation stories is a bit less narrow, I have a suggestion: Play around with the body-swap notion, see if you come up with any story ideas. And if you do... why not submit them to TSAT?