Today I will give some brief answers why Nobunaga built Azuchi Castle and stayed at the Honnoji later in his career. Gifu Castle was simply too far away from the capital to control the national stage. Azuchi was perfect for him. It was a convenience of transport of transport by crossing Lake Biwa and he could arrive in the capital in less than a day. Also Azuchi provided the Uesama to lead the front when at war.
Also there were two key points politically for Nobunaga. It was close enough to control the national stage and far away from the daily pettiness of the Imperial court. Nobunaga was smart to put his governor Murai Sadakatsu in charge of the daily affairs. For example, the President of the United States moving his headquarters to the mountains of West Virginia leaving the Vice-President in Washington to handle the affairs. Another reason why Nobunaga built Azuchi because the area was new and had no past history to haunt it.
Since Azuchi was built, Nobunaga had no legitimate reason why he should built a castle in Kyoto. The Honnoji became the Uesama's "Pied-a-Terre" or his temporary second residence. Again, it made sense because Murai Sadakatsu was Nobunaga's governor of Kyoto. Nobunaga only needed a second home when he visited the capital which drastically decreased later in his career.
Nobunaga no tame!