I do not know why people feel compelled to sexually assault other people but they do. If there is inappropriate conduct at a public place it is the fault of the perpetrator not the festival or whatever venue said acts take place, unless they are specifically promoting sexual assault against people.
The influx of asylum seekers into Germany is an unstable factor for the county and any violent event will fuel more anger. There recent attacks at the music festival were reported to be from Pakistan and this will create more unrest for the German population. It is difficult to blend cultures and accept new immigrants and this event gives more reason to resist the asylum seekers.
Yes, I believe eighteen women reporting being sexually assaulted at a music festival in Germany will fuel anti-asylum anger. Unfortunately, any sort of mass crime like this will fuel bigoted viewpoints and fear of giving asylum to middle eastern refugees. It doesn't mean it's right or ok, but it just is.
The recent assaults at a music festival are only going to add to the anti-asylum sentiment in Germany. People want to feel safe in their own country, and Germans increasingly feel that they are in danger. This leads to protests and general unrest, especially when the refugees keep rolling in.