I get why that's annoying for some, but this isn't that. The detached vehicle is it's own thing, and not just another Hot Rod - the POTP version did that, while this is a chunkier thing that's clearly aiming more for power than speed. Hot Rod's car mode is all sleek lines and very flat, while this is chunky, taller and very different in a number of places.
The length of the overall 'campervan' mode isn't because of the car, that's more of a stylistic decision. I'm glad they went with it too - most G1 Rodimus designs are too fat and stubby. Apart from the gap in the pipes, this is a great update.