Like I know, it took a while for legislation to follow Board v Education such as Civil Rights Act, Great Society, etc. But crucially, there were significant push by social activists and even politicians for societal change almost immediately after Brown for further civil rights and legislation. And even middle school textbooks point to Brown v Board as the crucial turning point for the Civil Rights Movement. But why not after the 1986 Supreme case? To my recollection, there were no significant state or federal legislation addressing sexual harassment until basically nowadays. American society after the 1986 case just seemed to shrug their shoulders and went off like usual. High profile cases like Anita Hill didn't inspire immediate societal push for change, so what's the difference between the two cases?
I can answer part of this question, albeit from a legal perspective. The Meritor Savings Bank v. Vinson and Brown v. Board of Education decisions are very different as to whose conduct was governed by the decision. And this difference is important in thinking about whether a federal legislative follow up would be useful after Meritor.
Brown ruled that under the Equal Protection Clause of the 14th Amendment to the U.S. Constitution state and local governments could no longer maintain "separate but equal" school systems segregating black and white children. Because Brown is a decision under the Fourteenth Amendment to the Constitution, it only regulates the conduct of state governments (and their subdivisions, such as Boards of Education and cities). Brown has no affect on whether non-governmental actors may discriminate against others. For example, a private school refusing admission to black students could not be said to be violating the U.S. Constitution. For another example, there is nothing "unconstitutional" about a publisher refusing to publish books written by women.
By contrast, some of the Civil Rights legislation of the 1960s that OP mentions in the question regulates the conduct of private companies and individuals. One of those laws was the Civil Rights Act of 1964, which was the law being interpreted in Meritor. One of the provisions of the 1964 Act prohibited private employers from discriminating in the terms and conditions of employment because of the employee's sex. So, for a fairly obvious example, an employer could not (legally) refuse overtime to women because the employer thought the women should go home and cook dinner for their husbands and children. The Meritor decision decided that sexual harassment was discrimination as defined by the 1964 Act. So, because the Court was interpreting and applying an already-existing federal statute, we wouldn't expect the U.S. Congress to pass a law where it had already done so.