Why is there still so much controversy over the evolution of humans from hominids?

I assume you speak of the true controversy that exists in anthropology. Basically this is an argument between " lumpers " and " splitters. " The lumpers want to lump all the various branches of hominids together in a tighter family, thus showing a ancestral progression that is able to be followed easily. The splitters cleave the various hominids onto many more species thus making it very hard to follow the ancestral trail. This is not meant to explain all here, but to give one reason for the controversies in this area.