It might not always be worth spending an extra 4 mana just to get a couple of land creatures, but it offers the flexibility to do it if you have nothing better to spend mana on that turn
This combo is most common in Pioneer, where Greasefang is among the top decks, thanks to how easy it is to fill the graveyard in that format
It only costs two ink to play, or characters with a cost of two or more can be exerted to play the card for free
This, combined with Hardened Scales, means if a creature gets +1/+1 for being summoned, it would actually get +3/+3
Such a high value for uncommon cards
In Modern, all three cards shown above have important roles in tier one archetypes