Corpus Christi is known to be the type of festival wherein people will make it a point to remember the sacrifice that Jesus has done for the people. This allows people to remember that the bread and wine that is usually shown during a mass represents the body and blood of Christ that he sacrificed when he died for the different people who have sinned against him.
This is still being celebrated right now because it seems that a lot of people have already forgotten the sacrifices that Jesus has made for them. There are some countries wherein this is considered to be a public holiday.
People celebrate Corpus Christi to commemorate the real body and blood of Jesus and his real presence in the Eucharist. This is done in remembrance of the Last Supper Jesus Christ had with his Disciples as stated in the Holy Bible.
The feast is celebrated by Roman Catholics and other Christians all over the world to proclaim the truth of the transubstantiation of bread and wine into the actual body of Jesus Christ, the Son of God during Mass. A day is set aside for this celebration. Hope you find this information helpful.