Give examples (other than slavery) of how it is wrong to accept something just because that is how things have always been done. (See below)A...

When a society has been doing things in one way for a long
period of time, people come to believe, without having to think about it, that that way
of doing things is morally right.  They will tend to defend it simply because it is
traditional, because that is how things have always been
done.

You mention that we should not use slavery to answer
this, but I would point out that the closely related issue of racial discrimination is
another example of this.  White people in America, as late as the 1960s, still simply
assumed that non-white people were inferior and should be segregated.  This was clearly
a case of something that was wrong being accepted because it was
traditional.

If we look at the present day, this is a more
controversial idea because many people will still believe that the tradition they are
upholding is right.  One possible example of this would be ideas about gay people.  At
present, gays are denied some legal protections and rights, such as the right to marry. 
This is largely because we have traditionally believed that homosexuality is wrong. 
Future generations may well look back at our times and conclude that we were stubbornly
holding on to a wrong belief simply because it was traditional.