There are two fundamental reasons.
First, if the person has a short temper, and possibly
has been involved in family or other violence, they
may have a restraining order on them, and it will
usually be in the civil litigation records. If the
person is being hired as a care-giver you must know
this. If the person is being hired to work in a physical
plant where a short temper can do millions of dollars
in damage like a refinery or a semi-conductor plant,
you need to check civil litigation history.
Second, the civil litigation records are where you
will find out whether the person is sued by everyone,
or whether they sue everyone that they deal with.