I think it is due to society suffering from the ivory-tower phenomenon. When people have no constant challenge to their worldview, they begin to assume it by default, and then they begin to use said worldview as an axiom in their thinking and research. This is sadly true even as far as government research. It is usually quite easy to see a given researchers political views in what is supposed to be unbiased research. Consider this as an example, most rape statistics rate made-to-penetrate and rape as two different things (under the assumption that made-to-penetrate has some differing experience to the man than rape is to a women [how the researchers are supposed to objectively make this assertion about people SUBJECTIVE experience boggles my mind really]) surprise, surprise, said statistics show that women are in danger of being raped in higher numbers (esp. on college campuses). Of course when one folds the two categories together this rape epidemic narrows to the point of vanishing (in fact colleges are actually safer than areas on the outside). In either case, it is not as if the researchers are attempting to be dishonest, nor is one method superior over the other, it simply is the case that one can make data support nearly any conclusion. This is especially true when politics are involved.
http://www.cdc.gov/violenceprevention/pdf/nisvs_report2010-a.pdf