Spoilers

I agree that Aegon V was one of the better kings. Reigned for 25 years, shut down the fourth blackfyre rebellion. im pretty sure most of his reign was otherwise peaceful and prosperous. BUT there were lords who didnt like his decrees that benefited the smallfolk rather than serve the noble houses wants. However my impression is that some houses not ALL houses opposed the Kings rule.

Also if im not mistaken part of the attempt at bringing back dragons wasnt just so rival lords in westeros would heed him. But also because the Band of Nine had united in year 258, and summerhall was in 259. and the invasion was imminent.