1. It lets your soldiers see you.I'll admit I am a bit confused on what the flying is here to accomplish.
2. Shows them that you have superpowers on your side, so surely you will win.
Thats just a normal monarchy except that in a magical world its not enough for a priest to say that rulers have a divine right to rule (or are divinity themselves) and instead the nobility has to go the extra mile and show that they are better than normal humans by developing superhuman abilities (=spellcasting)This sounds more like an evil magical overlord, than a normal magocracy to me.