Imagination is important for good writing, but it is not enough, in my opinion; writers have a social responsibility towards different groups of people, especially those without a voice, even the dead. I guess this is the main reason for the advice that it is best to write about what you know but it could also be the case that writers write about things they want to know, in order to find answers to what they perceive as burning questions.
This is where research comes into the equation and the first defining moment of good research is identifying reliable sources of information. Internet has made it easier for people to access and triangulate information so that different positions can be identified and examined as to how experts and authorities on the subject agree on some points but disagree on others. Through the weighing and considering of different points of view, a writer can develop his or her own perspective, or create and oppose characters who represent and embody different perspectives.
What makes online sources interesting for me is the ease with which they can invite the public to critique and challenge their findings and conclusions. History is in constant revision with every new archaeological evidence or release of restricted documents and it is easy for those who have been educated in the educational system of the past to hold on to incorrect ideas or misleading prejudices unless they actively keep up with the changing world. The attic of the mind is surprisingly vast (like the fictional castle of Gormenghast) and I'm often surprised to find cobwebs where I didn't expect them or new ones that had materialized even after I thought I had removed them, perhaps formed from residual materials.
Obligatory education is intended to prepare us for literacy and lifelong learning while higher education furthers these aims. As the pragmatic American philosopher of education John Dewey stated, we learn by doing. http://en.wikipedia.org/wiki/John_Dewey The more we dig and excavate what is hidden beneath the surface, the more we are apt to experience life fully as we find interesting facts and clues to contemplate and seek deeper meanings.
A writer, to me, is the archaeologist of the self and of society whose project is revisionistic in nature as an open and authentic quest for the possiblity of self-transcendence. In a sense, writers, who are serious about writing, knowingly or unknowingly aspire to be like the angels who are created to spend their lives listening closely to people's prayers and processing them into polished forms that can then be taken up to God.