I guess I see where you're coming from but I feel that it not being an installation or a short film was a key component of me being so shocked/uncomfortable with it. The sound design part absolutely has art installation vibes, but I felt being immersed in the mundanity of their daily lives, their little trips to the river, their lunch by the pool, the conversations in the house, the daily routine basically, was a big part of what the film was trying to achieve, and by reducing it to the format you mention, the impact wouldn't have been the same. However, I see this from the position of someone who was deeply troubled by it, if it left you cold I see why you wouldnt agree.
Yeah her performance in Anatomy was stronger, and was also really the only interesting thing in that film. I didn't know about her before this year even though I see she was in Toni Erdmann which has been on my to-watch list for ages, and in a Netflix film "Munich the edge of war", that I'll probably never watch.