All the officials and people addressed him as Regent Emperor, because his real power outweighed the Emperor. But Wang Mang was not satisfied with this, what he coveted was the real throne. So he took the throne and intended to build a brand new dynasty. He proactively made reform, implemented the new deal, he had so many beautiful visions, it was a shame his idea couldnt be fulfilled and turned out to be idle talk. People may not forgive his sin of usurpation. But as a politician, the effort he made and the political blueprint he tried to fulfill are all telling us his contribution to the society.