Because its news. And more often than not, news involves incidents like this. It may not be nice but it's important...
So if this was one of your parents, or your son or daughter, you'd be happy for them to be degraded to the level of a lumpy sheet in the gutter on national TV? Okay...
The image doesn't convey any information at all, therefore it is not 'important'.
It is a vague, covered-up body being shown as part of a very important news story. It may not be nice but it is important.
If they were identifying the body, saying "Majorie Bhamas, 58, was killed" whilst showing her body that would be different as it would be about her, not about the story. Equally you could argue referring to "five fatalities" or "at least five deaths" is degrading in that it's referring to the dead as statistics rather than people, not that I personally agree with that.
And it's not the news broadcasters who have degraded him/her to the level of a lumpy sheet in the gutter, but the gunman who somehow lacked humanity and put a bullet in them.
Fiona Armstrong giving a lot of information about the region - not entirely sure how relevant some of it is but nevertheless interesting.