Yes there is the Pathfinder, but that is too late. lvl70+? Really? Every game has weekly quests (but not at the end game) You must play 1-2 year until you can do weekly quests. Nice . Yes BB describe in AMA why they did it, but they could consider it reduce the level. Different quest, different reward, but decent at that levels. It would be great pathfinder from lvl50. Why? Just check the quest list from lvl50 few quest/lelvel, and after lvl55+ the quest log is almost empty.
Build, buff, collectible every day. + adventure Grind -> exp. They need to introduce decent exp rewards from different part of the game. Weekly quest rethink would be a good part
Gems for weekly quest? Maybe yes! Very good idea!! But then delete from weekly login reward, and 7. day login would be more crystals.