Certainly protecting the head is a priority. An example would be a single leg takedown from the ground where I see MMA guys training to grab the ankle with both hands. I teach it with one hand grabbing the ankle so you still have one arm up to protect the head. On the ground against multiple attackers again I stress keeping the head protected and to keep moving.
Escaping from pins and locks is an interesting point. Generally it is not taught in Aikido until about 3rd dan. I teach it from the early stages as knowing how to escape means you learn better how to apply the hold.
As to whether these elements were in the original Goju ... I believe almost certainly. Although Higaonna didn't name Goju he started Naha-te, its forebear. This was the combination of the Kung fu that Kanryo Higaonna became a master of in China and the local wrestling type fighting that had developed in Okinawa, Tegumi. Chojun Miyagi was his student and obviously learned those things from Higaonna. Miyagi also studied Judo in his early years, something he obviously encouraged his students to study also. Jinan Shinzato, Miyagi's top pre-war student, and Eiichi Miyazato, Miyagi's successor, were both highly trained Judoka. Miyazato's student Masaji Taira, ex Jundokan and now teaching around the world, is also a highly trained Judoka and is teaching this hands on style of karate.
You might say these guys trained judo to fill in the gaps but I would suggest it was more to better understand what was already there. I started Aikido for that same reason.
Then you look at the Bubishi. It has many illustrations of grappling. Even more telling is the section on vital points and pressure points. Obviously some are for striking but others are activated by pressing or rubbing, something you need to be actively engaged to perform.
Of course that raises the question, "if it was there originally, why don't you see it now?" I think that is because of the mass training style that was adopted to teach karate to the masses. Hundreds of students lined up and moving in unison. Easy to teach kicks and strikes but difficult to teach complex grappling techniques. That is characteristic of Japanese Karate but not so much in the Okinawan style.