Why do the women run 10k? There are plenty of 10k road races, why not make it the same as the men?
Not sure about this, but one thing is to give women a stage to show themselves. It's a different race during the same event, where they are the headline act. With a 10k it's easier to get a large womens' only race/fun run.
In fact, in the previous years the professional emphasis was even a bit more put on the womens race (try to be the fastest 10k in the world) than on the mens' 10M.
Men aren't allowed to race during that 10k race. There's another 10k fun run for them. Women can participate in the 10M event, but only as fun runners.*
* in the Netherlands there's still a official distinction between a competition and a recreational 'race' or funrun, although those races can start at the same moment.