 According to the original script, the character of Kreacher was not  intended to be in this film at all. But after J.K Rowling read the  script, she more or less insisted on him needing to be there to  avoid some serious problems with future installments of the series.  So, even if Kreacher still has no noticeable impact on the plot or  story as its presented in the film, a couple of scenes with him  were added at the last minute based on this request.