Mainly to get rid of leak POS quick connects. Those o-rings are a ***** to replace and not worth the time IMO. Besides, with aftermarket rails the braided line looks way nicer, but thats beside the point.
Another reason to loose the OEM GM disconnnects is to get rid of the potential fire hazzard for good. Several of us believe the GP fires are from the quick connect o-rings instead of the valve cover gaskets.
Hope this helps...