Commissioned investigations?

Today I heard a report ont he BBC about a study "commissioned" by the BBC on immigration trends. The subject was not as important to me as was the process. I thought about the few times that I hear those words - commissioned study - used to describe something that a newspaper has professionally undertaken to do. Why is that? Sure, there is expense to do massive studies, but there is little expense in doing small studies very well. It is, it seems to me, something that could distinguish a newspaper better from the pajama-clad blogger than is now the case, no?