we saw devastator in ROTF and he turned out to be okay because the vehicles he is made up of are extremely large. That is not the case for combiners like Defensor, Menasor, and Bruticus. If they were like their G1 selves, they would only be slightly taller than starscream or megatron. How would they be able to put these combiners in a movie and have them be huge without making them be made of 20 smaller robots??