1)There is an Iinyan for yidden to wear white,
especially Shabbos & Yom Tov.
(dont know about the black however.
2)bnei Torah wear black & white because
they are respectable, & should dress appropriately,
Lawyers, etc. businessmen, (old school that is)
I believe the Rabbonim of old also wore what was considered
respectable attire.