This is partially an opinion question, so in that sense, I cannot give you a concrete answer. However, I can offer my opinion in the hopes that it will be a good jumping off point for your own thoughts.
My own perceptions of the foster care system vacillate between very positive and a bit wary. My perception of it is largely through media rather than personal experiences, which definitely influences it. I understand that foster care is a great way to help children transition between difficult, abusive scenarios and into more supportive ones, but certain media makes foster homes seem like a relatively scary place.
I believe that perception differs between cultures based upon the amount of personal experiences that are within your social circle regarding foster care, as well as what media the people within that culture absorb. For instance, an upper-class family may have associate foster care with poverty and abuse and therefore have a very strong negative connotation. Those in lower income brackets may know people who went through foster care and emerged into happier lives, giving them a better perception. Additionally, these people may be exposed to less media that makes foster care seem frightening or bad (think of stories where young children get adopted into families that are mean or abusive).
In terms of the sociological perspectives and how they relate to the question of child welfare, we should consider the following three: functionalist, conflict, and symbolic interactionist.
A functionalist perspective emphasizes the family model and how important it is for society, so it would likely be supportive of child welfare, as it helps create order within families and makes society filled with less unhealthy families.
A conflict perspective understands that there are a great deal of inequalities in society and that they must be strongly addressed. This perspective would likely be supportive of welfare and foster homes, as they can help children stuck in situations that breed inequality (low-income, unsupportive, or abusive homes) by putting them in situations where they can succeed, breaking the poverty cycle that is created by a capitalist, racist, and sexist society.
Finally, the symbolic interactionist is focused on symbols and interactions within a family, such as shared meals, jokes and conversations. Foster homes and child welfare can be viewed as both positive or negative from this perspective. In one sense, taking a child from a family prevents them from having those crucial interactions and building important bonds. However, it could also be positive if they are placed into a family where those bonds could be more readily made.
This is a lot of information, but it should be enough to help you make your own opinion on the subject and answer the question. Good luck!