I was having a conversation recently regarding Bumblebee from the Movie continuity. He asked me why doesn't Bumblebee chose to become a jet or something with flight capabilities, I then explained the lack of mass-changing within the Movie continuity (With the exception of the All Spark). But it got me thinking as to why Cybertronians with suitable mass, such as Brawl or Optimus, aren't able to transform into flight vehicles. I would imagine that it has something to do the technology available to them, like Starscream and Blackout had alt modes capable of flight whilst they were still on Cybertron. Does anyone have any other further ideas about this that could help with this explanation?