The only downside I could of think of at the moment is new players that just reach level 70 and complete the MSQ (to start obtaining the new tomestones) would have instant access to high ilvl gear as they could just save Poetics and then buy a ton of stuff (to equip or mats to sell) when the requirements let them. It's really not that difficult to complete HW relics and I never thought that Poetics was ever an issue, so perhaps your method just needs to be adjusted OP.