I dont understand why there is confusion about why humans tend to see good looking people as good
There have been countless studies about how humans see other humans, how attractive people tend to have more friends, do better at school, do better in jobs, be more attractive to partners etc etc
We are an animal species, a huge amount of our interactions with each other are on a sub concious level and its instinctive in us to seek out or view more positively those who look fit, healthy, symmetrical, happy, confident and 'like us'
In particular in criminal cases, particularly murders like this, generally speaking the perpetrators were 'odd', they nearly always are, they look odd and they act odd and their history is odd. Thats because odd people do odd things, not always murder but generally speaking.