Why not a Secretary of Social Security?

Yglesias highlights a poll describing what people think the federal government spends its money on. Education makes up only about 2% of federal spending, but many people overestimate the amount:

The federal government spends almost none of its budget on education, and the vast majority of Americans massively overestimate the federal commitment. This is why for federal education policy to be effective it needs to use federal funds as leverage to change the ways state and local governments use their money...

I'm not sure I would have correctly identified that federal spending on education was only 2% of the budget. The funny thing is that Yglesias reads this and thinks it means the federal government should use that 2% to induce state and local governments into spending even more, a horrible idea. I read the same figure and ask: Why do we need a cabinet secretary for education if it makes up only 2% of the federal budget?

I mean why not use federal spending as a guide to which agencies get cabinet level representation? If we did, we would appoint a Secretary of Interest on the Debt (8% of federal spending) before we appointed a Secretary of Education. I can't help but wonder if today's schoolchildren wouldn't be better off under such a system.

We would still have a Secretary of Defense, but we would also have a Secretary of Social Security (21%).

Now that Social Security is running a deficit, wouldn't it be nice if we had set aside money from all those years when it took in more money in taxes than it spent in benefits? Instead all we've got is a pile of I.O.U.'s.

Maybe having a Secretary of Social Security wouldn't have made a difference, but on the other hand, I'm not convinced having a Secretary of Education did either.