I think the thing about the lack of noses is that it helps create a definitive TF look that carries across character designs and helps define them as distinct from other kinds of humanoid robots.
Like the Gundam faceplate + v-fin combo sort of.
See for me, that definitive look has more to do with designs looking like they're made of their alt mode. That's not a hard and fast rule, and there's plenty of exceptions, but in general I find that to be what separates Transformers from other humanoid robots, including other transforming robots. A lot of traditional Japanese transforming mecha tend to turn into vehicles that look like a folded up robot; where as TFs look like an unraveled vehicle, creature, or other things. It's like the robot mode is the primary consideration of most of the former, where the vehicle is for the later.