The passive voice seems to have fallen out of favor over the years and I don't really know why.
When I was in school, the passive voice was encouraged among other reasons, it conveyed the humbleness of the writer. These days, the passive voice has even carried over to scientific and technical writing.
For instance, it is also advocated here (note the use of passive voice is to sound less accusatory). It is also encouraged here for the following reasons:
We find an overabundance of the passive voice in sentences created by self-protective business interests, magniloquent educators, and bombastic military writers (who must get weary of this accusation), who use the passive voice to avoid responsibility for actions taken. Thus "Cigarette ads were designed to appeal especially to children" places the burden on the ads — as opposed to "We designed the cigarette ads to appeal especially to children," in which "we" accepts responsibility. At a White House press briefing we might hear that "The President was advised that certain members of Congress were being audited" rather than "The Head of the Internal Revenue service advised the President that her agency was auditing certain members of Congress" because the passive construction avoids responsibility for advising and for auditing.
Yet, the active voice when used can lead to criticism such as this where Tyler Cowen is apparently reprimanding John Taylor for his over-use of I in Taylor's memoir Global Financial Warriors. My theory is that the rise of the use of the active voice coincides with the rise of the Internet, reality TV and in essence the ME generation.