Gen1 Optimus/Convoy trailer/repair-bay origin?
I was commenting on this at another site, and figured I'd ask it here to see if anyone here has an insight into this puzzle.
The Generation One Optimus/Convoy comes with a robot, Roller and a Trailer/combat-deck.
In some versions over the years, and possibly only with JP versions, the trailer/combat-deck has been given a third mode - a repair bay... in which it stands up on its end when opened, and the Optimus robot can be placed up against it for repairs or maintenance.
The Hybrid Convoy has it, Gen1 MP-4 has it, Gen1 MP-10 has it, and even the recent JP DotM Voyager Optimus with trailer (not yet released by Hasbro) had this stand-up feature... so what exactly is it homaging for it to be an included feature? (an image of the original Convoy/Optimus in his repair bay, for reference)
The tfwiki (linked above) didn't make any mention of its origin, like if it was a carried over Diaclone feature (to repair their non-sentient robots) or if it was a plot device in one of the various JP-exclusive comics.
Any thoughts or suggestions on the origin or point of it... or even, why they keep homaging it if it never existed in Transformers?