why was palace moved to beijing from nanjing after zhu di seized power?

It's said that Zhu Li lived many years in Beijing and missed his hometown, so moved the capital there. Also the northern tribes were the biggest enemy during that time, so he moved the capital aiming to defend his country on his own.

Personally, he's derserved to be listed as one of the emperors with high achievements. Although he usurped power from his nephew, he did make achievements to his country by carrying out some beneficial measurements. His people lived a peaceful life then.