The complete lack of any negative aspect to the ring tempting you is just too much of a flavour fail. Maro says that players would not have wanted to use the temptation mechanic if it came with a downside, then they really should have scrapped it and tried something else. Even including some punisher cards that thematically could have introduced a lose condition from being excessively tempted would have been something. But honestly, given how baked in the concept of "undercosted spells or abilities with a downside" are to Magic, I refuse to believe that a free effect of the ring tempting you and giving you a benefit but also a malus would have been unused. There's whole deck archetypes built around that..