Regular side quests give more XP/gil than levequests is because they can only be done once, if they were flagged for repeatability you'd see their XP/gil rewards get slashed by a huge amount.

Battle craftleves are somewhat fine, a TINY (and only tiny) boost to xp is required for them, as you get a bonus for speed of completion, a bonus for difficulty and an extra bonus on top if you kill a special bounty mob that has a chance to spawn during each leve.

And as for people saying they ran out of quests as they got higher level, I have tons of high lvl quests left over, plus other new players who DIDN'T fate grind have several 45+ quests left over too. The system isn't based around you only doing sidequests it's based on you mixing a bit of everything together.