Frame changes are painful.
Everyone knows that but they think it's like getting a tattoo or a piercing. But that's because most bots who get frame changes only slightly alter their form. Like a bot with a regular car mode transferring into a race car frame. It's a bit painful, yes, and takes getting used to but it's still, ultimately, the same relative shape and within the same size range.
However any frame change more dramatic than that becomes more complicated.
Going from a car to a boat or vice versa requires multiple sessions with a doctor, alterations to weight and materials, and even after all that the bot has to get used to exclusively traveling on different terrain and learn all the dangers.
So, as you can imagine, going from a giant Decepticon attack helicopter to a much smaller autobot speedster frame is an alteration so drastic I think most in universe doctors would dissuade their patients from taking on such a sudden change. Even pre war.
So it's fun to imagine tfa Drift doing just that using a back alley doctor whose never even heard the term physical therapy, gave him no anesthesia, and kicked him out the door the second the operation was done.
Yea I've settled on Drifts frame change being a painful black market job that still gives him trouble even now.
Because drama.
