"Kaus kaki hitam."
Noun and pronoun are not the same. Pronouns don't get adjectives - you don't generally say "strong I", and so "saya kuat" is not ambiguous. I don't know Indonesian, but in Hebrew "socks are black" has to have a copula, so assuming Indonesian is like Hebrew, this can only mean "black socks".
Indonesian does not require a copula, indeed it is debated whether it has one. The adjective in this case would not be modifying the pronoun, which is in the possessive position. I do not know why this couldn't be a sentence either, though an Indonesian might use ada or adalah for clarity, I guess.
True! We (commonly but not in all cases) translate 'is/am/are' as 'adalah'. But it sounds acceptable when (in English) the sentences have 'Subject + is/am/are + Noun', like: "That is my book" -- Itu (adalah) buku saya or "Those are my pencils" -- Itu adalah pensil-pensilku. We don't differ 'that' and 'those', also 'this' and 'these', by the way. :)
In different cases, when we have "Subject + am/is/are + Adjective", it is best not to translate 'is/am/are' as 'adalah' because it will sound weird, both in formal and informal conversation. "I am beautiful" -- Saya/aku cantik. "That red t-shirt is expensive" -- Kaus merah itu mahal.
When we saya "saya adalah kuat", it will, somehow, tell someone that you are 'strength'; not defining that you are strong.