First, the art of calligraphy is the most exquisite: taking the law. Only by carefully copying the works of the ancients can we absorb the highest artistic essence. What ordinary people write (in theory) is not as valuable as others, because it can't reach by going up one flight of stairs in the calligraphy field in past dynasties.
Second, even works copied by the people vary from person to person because of personal cultural accomplishment and aesthetic comprehension of calligraphy. It is better to copy the original tablet directly. Why did many people in ancient times accumulate so many Prefaces to Long Ting, including Mi Fei's, but only Feng Chengsu's is the best in the world of books? That's the truth.