Just a thought..

[ColorOfSakura]

Basically every dungeon once you hit Level 50 is not part of the main story. In fact, it wasn't until 2.4 where they even brought back story dungeons for level 50 players (Snowcloak and then Keeper of the Lake in 2.5)

Everything else has been optional. Full party content also has both optional and required story bits - Castrum & Praetorium are obviously required, as are the Hard Modes for King Mog, Leviathan, Ramuh, and Shiva.

But Odin, the various Gilgamesh/Hildibrand fights, all of the Extreme mode Primals, and both the Crystal Tower and Binding Coil raids are all optional.

I feel they've struck a fair balance.

I don't really think the dungeons are the "main draw" of the Main Scenario. They just exist there to get players used to party-based play during low levels alongside stuff like Guildhests. Honestly, dungeons originally gave almost no experience and very little gil. There wasn't really any "rewards" for doing them until you hit Level 50 and were earning Tomestones.