am sure you are right, as far as ordinary Japanese is concerned, but I do not think this principle was applied by Morihei Ueshiba to aikido. For example, taking the classification of omote and ura techniques in Karl Friday's "Legacies of the Sword" as an example, would you be prepared to classify aikido into "plain" and "hidden" techniques? I think this is one aspect where the Founder broke away from classical koryu such as kashima shin-ryu.
Sorry, I don't do Ueshiba Aikido. I would not know if Ueshiba had another interpretation for these terms. I learn Korindo Aikido and our terms in this case come from the Koryu. We have borowed some of the Aikikai terminology in my dojo, in cases my Sensei didn't know the Korindo term, I don't know if that is because Hirai sensei did not bother much with the terminology or because my sensei did not understand it when he was learning in Japan. Some of our local terminologi was coined by my Sensei and later corrected when a Japanese Shihan came to visit.
Another thing to think about is that sometimes the "plain"/ "Omote" technique allows for later timing and goes with Uke direction while the "hidden"/ "Ura" techique requires an earlier and more exact timing and goes against Uke direction. But, this is only true to some variations of the techniques, not all. I can point to cases in which my favorite Omote excution is based on trying an Ura aplication and failing (this is very common in Ikkyo for example).