"Не суди о книжке по её обложке" - в переносном значении

In my opinion, its vital not to judge anyone on the basis of appearance and I think so for the three following reasons. First of all, having such a mindset creates lots of prejudices and stereotypes, which is not something to be proud of. Secondly, judging someone by the look limits ones communication circle, which may be disappointing in the nearby future. Finally, its just morally wrong to not learn more about the person and criticize him or her because of the qualities that the person did not even choose.