Hajj and the Hazrat Ibrahim episode are two entirely different things. Muslims have mixed these two things and have created a new form of worship. Hass was originally meant to be a political affair and not a religious one. Under Hazrat Umar's orders the governors of the 6 provinces and the other leaders, with their delegations, came to Makkah for deliberations, a kind of an annual general assembly.
Proves that all religions somehow cannot get rid of the old concept of god/gods and sacrifices. If Muslims really want to follow the Sunnah of Hazrat Ibrahim, then they should sacrifice their son and see if the sacrifice is accepted by God.