>>7347357greebles are used to break up large, flat surfaces
so on a titan transformer, they make perfect sense. It adds interesting visual variety
On smaller things, it doesn't make any sense.
For transformers, while they are large, they're not THAT large. Optimus' knees down are about the size of a human. You wouldn't expect a coffin to have a bunch of panel lines and various other details, would you?
That is, if it's used to represent manufacturing.
Now if they were intricate but designed to make something have more class and value (like megatron's spiral chest marking) then it's fine.