It just flowed so well and had the added benefit of naturally combining with abilities like support that reinforced the cooperative nature of the game. As an added benefit, these simultaneous turns make Illumineers Quest: Deep Trouble a great way to teach the games core concepts to new players
He has a high cost, but can quest for three lore
That's already a strong floor
Of course, you miss out on the adventure if you have to just run this out as a land first, but thats nothing a good ol Kor Skyfisher cant help with
Without these safeguards in place, older cards can often become huge problems for modern competitive play, especially because newer cards will have to abide by those restrictions a lot more consistently
For instance, Halvar, God of Battle from 2021's Kaldheim wasn't the most valuable card when it first debuted, but with the launch of the Final Fantasy crossover, its value has shot up