You may have meant to. However, that is not what you wrote. You said "We may have treated the Complete 2e books as optional but that is not how they were presented." And prior to that you wrote
And, that is what I responded to with regard to 2e and the Complete books.
However, even what you are saying now is still not correct with regard to 2e. As one or two other posted, there were core rules in the 2e PHB and DMG along with the addition of optional rules that the DM could choose to allow or not.
I am not commenting on 1e. It has been too long since I have looked at the books despite having copies my friend left me when he moved cross-country. If I get the chance, I may dig out UA just to see what it says or doesn't say about being optional.