Orion Pax had the servos of a data clerk. Light, slim, and graceful, they were servos meant for typing.
Over the course of the war, Orion’s - then Optimus’ - frame was heavily modified . Arms and armor added weight. Struts were reinforced, actuators were stabilized, joints were hardened. A thousand different enhancements increased his readiness for war.
Servos are usually made to better help a Cybertronian perform their duties. Jobs that require/d more hands on work or a specific kind of hands on work (like typing) were often worked on by Cybertronians who were built with specific servos, or who had modifications to their original ones.
I’ve written about this before, but to Cybertronians, the idea of organics being affectionate to other organics is probably similar to how the idea of hearing metal scraping against metal is not how I envision a happy partnership that’s gonna last thousands of years.
When a Cybertronian takes on a new altmode, especially one that’s very different from the previous one, the only things that always remain the same is their paintjob, servos, and optics.