In Magic the Gathering Origins set, there is a cycle of 5 creatures, each that are double-sided and have a planeswalker on the back side. Previously when double-sided cards were used, the cards had a condition that when triggered, said to "transform [CARD NAME]". However, with this cycle of cards, instead of simply being transformed, when the condition is met, the cards are exiled and then returned to the battlefield transformed.
Is there a reason for this? There's obviously a few different situations in which case this will be different for game purposes, such as if the creature was being targeted by a spell on the stack when it's transform condition triggered. But most of the time it would play out the same. And the new version is a little wordier than the old, as well as different than what people were used to; so I'm assuming that there's either a mechanical reason or a flavorful reason for doing it this way. Are there any rules issues that would be caused by a creature simply transforming into a planeswalker?