Food isn't enough, I need to chew through solid concrete to be s

Starting off, I referenced CYLAS' canonical pedipalps to try and understand the shapes being used which resembles a lapping type mouth that bees have (so considering there is a tranformers character named Bumblebee it feels appropriate but he ISN'T HERE), let alone the flexible proboscis which I just made as a siphoning type from butterflies which; this is the wikipedia image I used to understand mouth parts :P

Breakdown himself wouldn't need to open his whole face in order to consume energon, given that he has an opening and closing jaw in addition to having the dexterity and power of limbs and a neck to not require lapping, but energon is still drunk through the proboscis like a straw.

Continuing onto characters that would NEED their pedipalps, vehicons and other faceless cold constructs (whether you have the belief every cold construct is faceless or they recently shifted to facelessness to save on costs) by technically did not metamorphose like forged mecha and thus their mouth parts have not gone dormant. Instead, their construction means they have not known anything other than pedipalps and proboscis, having no experience at all with facial expressions and thus not susceptible to phantom sensations.

Though their jaws do not have joints or at least do not have an opening to function like an enclosed mouth, vehicons still do have one on the basis of having a neck and a location to store their coiled proboscis when not in use.

Unlike other cybertronians - forged or constructed - empurata survivors have their heads and/or faces completely remolded and restructured where they do not have a functioning jaw. They have in it's stead a reconstruction of the original pedipalps formatted appropriately to the new head mould.

Monoptics like Shockwave do not have enough room in their helms to have a mouth-like structure at all, instead the neck is reconstructed to open with the pedipalps; the proboscis when fully extended appears longer in monoptics but that is due to the fact the opening is lower and closer to it's base. Nulloptics like Soundwave have their entire face replaced by their mouth, often covered up in seamless panels that give the appearance of a screen, up until the nulloptic actually replaces the panels to include the electronics necessary to protect and display visuals.

In average adult cybertronians however, the pedipalps remain dormant - at least in their use for eating - and are instead used to produce vocalisations alongside the proboscis (which still remains in use by function of the liquid energon diet), in addition to being used in expression in conjuction with the many servos operating within the faceplate. The reason why, despite the variety of things pedipalps can do now that they aren't being used to consume fuel, that empuratas and constructs cannot re/gain a face with the same ability and level of complexity of the average cybertronian is because of the hyperactive function of those very pedipalps.

Vehicons can - if they so choose - express visually through the exclusive use of their pedipalps, but factoring in a faceplate with all of it's own complicated servos intricately woven into each other, the faceplate lacks the ability to split along the seams of the pedipalps and would restrain their mobility and prevent the cold construct from refueling. Empurata have a similar issue with the addition of their lack of functioning jaws and their modified head structure preventing the synergy of a faceplate. Nulloptics' heads are functionally all mouth so the corresponding faceplate cannot have features for optics or ridges, and monoptics' pedipalp expression is on their neck and thus a faceplate that matches where the mouth in their case would be a very bizarre choker-