It's not obscure. The reason is because a whole class of racist laws use the term. Nobody has seriously tried to reclaim the term, so it is stuck with the connotation it had developed a hundred years ago.
Genuinely curious which class of laws that would be.
I assume you mean in the US but the 1882 Chinese Exclusion Act makes no mention of race and anti-miscegenation laws speak of Mongolians(presumably to mean people of East Asian ancestry in general).
I think Oriental in the US like the alternative Asiatic applied to all Asians from Istanbul to Vladivostok.
