Also in the same report, it may be seen that the girl was taunted by the rapists questioning her what she was doing so late in the night with her boyfriend. It may suggest that the rapists might have thought that the rape was justified as the girl, in their own opinion was, having an illicit relationship before marriage. This sick attitude is more a cultural thing, where women are expected to be chaste. For other such examples, try a google search. This moral policing is an ongoing phenomenon demonstrating such attitudes.
Your post is as good as any to quote, since you mention the attitude of culture and moral policing. Societies evolve generationally with the younger not having as much root into the same beliefs as the older people, and whether the changing beliefs are better or worse is an open question. This sad case may inspire a political movement to assign better quality to the role of women in the country.
Besides cultural, there are economic and legal issues that come into play.
Not so long ago, 40 or so years, a rape victim in N.America ( generalization ) had to prove to the court that she (he?) was completely innocent in not attempting the morals of the accussed by dress or manner. Past history of the victim could be brought in as evidence that she was of 'loose morals' and would have known what situation she was getting into from 'experience'. Failure on her part to not lead a puritanical life, provocative clothing, being at a place where a good girl should not be, could all be used as evidence to gain the aquital of the accussed.
The legal issue was adressed by reclassifying rape to sexual assault therby removing stigma and disallowing such sort of evidence in court, as descibed above. But that took years to bring about into the legal system and change attitudes of law makers (ie politicans ), lawyers, judges, media.
The economic issue is that of what role do woman play as 100% members of society, or are they? Nowadays, in N.america again, woman over the years have progressed , if that is the word to use, from being 50% citizens with no right to vote and no chance of acceptance into certain vocational activities to having the right to choose what they can do, and can go so far as being an astronaught flying into space. The reasons and history of the womans movement comprises as very, very long discussion.
Perhaps this case, where someone had to die, will be the spark to ignite enough continious momentum to achieve some change that is being expressed as desired, both here and as evidenced by the protests in the country.