What might work out better is a EXP boosting potion (or script) that only works for certain pre-current content Expansions. Like a "300% EXP boost when under level 50/60/70/etc" item to help speed new players along while reducing the number of fluff quests needed.
When I leveled up my alt, I'd found that the 2.0 MSQ quests are already pretty much doing this. I didn't need to grind fates, dungeons or levequests (aside from ranking up in my Grand Company. That needs a boost tbh). Heavensward could do the same. They've already cut a lot of the fat out of recent patches to better streamline people getting into content.
When I leveled up my alt, I'd found that the 2.0 MSQ quests are already pretty much doing this. I didn't need to grind fates, dungeons or levequests (aside from ranking up in my Grand Company. That needs a boost tbh). Heavensward could do the same. They've already cut a lot of the fat out of recent patches to better streamline people getting into content.