FFXV was not a bad game, but it was a complete mess. Unrefined and chaotic battle system, (lack of) character development, too much travelling by car or enduring the very long loading times, needing DLC to have stuff fixed, bad second half, bad side quests (don’t even get me started on the cup noodles one)…
My main gripe is that the biggest plot point in the game, the fall of Insomnia, was just to a few seconds of cutscenes. If you didn’t watch the movie, you couldn’t care less about the city. Also, the whole character development of the other 3 main characters other than Noctis was only in the anime or in the DLC. If you just play the game, they have no character development at all.
All of its aspects show that it’s just a spin off game that got stretched too much for its own good.