>>6282634Easier to make loose pieces that move around with large gaps.
Making a humanoid face with smooth motion and fine seams takes effort, time, aesthetics, and skill.
Just compare to the transformations; as in the 3D doesn't transform, it is achieved with multiple swap-in models, scene changes, shot transitions, and blurring.
Presuming the level of technology Cybertronians would be composed of (magic alloys activated by bay-radiation) 3D models could be constructed that actually transform without model swapping and SFX, but the engineering cost and time would only allow 1 or 2 for the movie's budget.