What convinces you of its importance?
The constant stream of terrible policy decisions that anyone with a basic knowledge of the state of research in a field would have known to avoid. Education policy is probably the biggest victim, but there are examples everywhere.
So why do you think that social research has such little influence on public policy? What would you do to increase its influence?
I know when I was in grad school for mathematics a few decades ago, it was not unusual for the profs to make fun of social science papers that had made bad use of statistical methods. Hopefully, the situation has improved, but it certainly had to have had some effect on why social science has been sometimes ignored.
