If you want to grind for exp or crystals in there, use it. Cause god forbid there's content inside of an MMO that requires you to talk to other people right next to where you are in the game... I wouldn't know about Eureka, but I'm pretty sure it was required to finish the ...
How does rested EXP work in FFXIV? If you are not logging, or you are offline or AFK for a bit, the rested experience will give some experience boost to all your classes, independent if they are combat jobs or non-combat jobs. If you see the icon moon next to your experience bar...