Rather than blame one culture for the failings of another culture, why don't Sociologists study the root cause of poor cultural development?

Psychology can do that pretty good too.  Put both together and there you have it.  The study of the individual social being called human.  Getting to the root cause of anything like that may require more than just a psychological and sociological degree.  It may require a medical degree also.  Then we have neurologists who need to study other sciences just to get closer to understanding their own science.  If you really want to get complicated, get everyone involved.  Each will have a little part of you in their own private test tube or laboratory of clinic. The only thing missing is you.  You are the only one with all of you.  And to understand all of you?  Good question.  I barely understand myself so I am no help there.  Being the root cause of poor cultural development, I think they already studied me and came to the same conclusion.  Lost cause.  

hello. How do you define poor cultural development? From whose viewpoint? Which country's sociologists are you employing to study the cultures? is there are bias in the nationalities of the sociologists?

There is no right or wrong answer to one's culture. Each cultural group has its quirks.