Having been an Aurealis Awards judge … there isn’t any conscious decision towards what sort of stories win awards. A lot of things are going on with judging any award.
There is a panel of judges, but it just takes one nay-sayer in a panel to knock down the front runners in a close run race. Or, a person on the panel drops out halfway through the judging period and the rest of the panel is scrabbling to make sense of the mess left behind. The smaller the number of people left, the more likely it is that personal taste will affect the end result.
Lately, what I see happening is that the darker, more literary stories are being accepted by the magazines and anthologies – thanks to the popularity of GoT and its darker themes. Fashions in writing happen just like in any sort of human-based activity- just more slowly. Ten years from now, we might be looking at a retro-revival of sword and sorcery or space opera. So, it is these darker stories that are winning the awards.
A good story is still a good story. Do your best to write amazing stories. You might not win awards, but you will get nominated for the short lists over and over again. That is more of an indication of the quality of your work than anything else.