While Expressive Iteration technically only replaces itself as far as cards in hand are concerned, it's the perfect spell to drop on turn three in a land-light hand, in order to make your land drop for turn and set yourself up for turn four as well
It does everything, between its Treasure production, card draw, and board presence
We track 159 singles in Morningtide
Late game, this is a way to dig even deeper to grab that game winning Overrun spell
This, combined with the fact that there's a lot of competition for Nature's Rhythm's slot in eternal 60-card formats, should help keep its price down, which means that the floor of Nature's Rhythm is likely as a very strong budget-conscious replacement for something like Finale of Devastation
A: Ive seen some pretty ridiculous cards get graded