Final Fantasy XV Is actually trying a new approach of mature storytelling. Said to be deeply exploring the human emotions and misery but through light hearted and close relationships and not typical dramatic approach.
The game kicks off at the ending of a long cold war between nations over the source of power (the last remaining crystal) which belongs to Lucis, Noctis's kingdom, an advanced and isolated country that use magic and forbidden to use guns. The outside world is the exact opposite of that. The other sources of power have all been consumed on war and political matters not to develop technology and income. They use guns and not magic.
There is also the love story with Stella/Luna, and the complications of going through war with her kingdom. A lot of plot twist potential there.
Also, Noctis seems to be in good terms with his father. The king was goofing and joking with Noctis as a kid, this was revealed in two different trailers. So what gave you that idea?

If you are interested in more story details :
http://gematsu.com/2010/08/final-fantasy-versus-xiii-all-the-details-so-far