I think that Frith's word, improve, is used in relationship to expression of an idea, art.
Art does not necessarily need to "tell the whole truth". In my mind neither does photography, that expectation is artificial. That expectation may be of value for a news organization but for the rest of us it is more a choice about our style than something that is right or wrong.
Even the f64 crowd can't be said to be representing "the whole truth". Compare the straight versus the final prints of Ansel's Moonrise and it becomes hard to think hat Ansel was telling "the whole truth" rather than expressing an idea. http://www.jimalinder.com/portfolios...onrise.psd.jpg
One of the big drivers of soft focus photography was that through improvements in technology, resolution had gotten "too good". The lines and imperfections in a sitter's face had become a real problem for portraitists, just as they are today. Soft focus helped keep studios in business because, as sexist as this may sound, women don't generally buy portraits that make them look fully their age or portray their children with a bunch of zits. Right or wrong, Portraitists ignore social norms at their own commercial peril.