IIT Kanpur got rid of their integrated M.Sc. program a few years back and replaced it with a 4-year B.S. program. I don't know the exact motivation but my guess in choosing a 5-year int. M.Sc., the motivation was to include a research/project component in the degree whereas a 3-year B.Sc. degree has no research/project component in it. So, all undergraduate degrees given by IIT include a research/project component.
Maybe, Prof. Dheeraj Sanghi can shed more light on this topic.