Playing cards from the top of your library both preserves the cards in your hand for later use and serves as pseudo card draw that digs deeper into your deck so that you can find your bombs
sacrifice decks often go wide, which makes them vulnerable to board wipes, so a synergistic way to get your best cards back has value
Dinosaurs on a Spaceship lets you cast it immediately for 6 mana or suspend it and slowly but surely get a dino army along the way
Geistcatcher lets you perform disgusting creature loops, and works as a spare piece in countless combos, given you can tuck a creature that can reanimate Geistcatcher under the Geistcatcher
Sevinnes Reclamation gives White a sorcery that can not only fire off Sun Titans ability once in isolation, but twice from the graveyard
The real power is that whenever you gain life, you get to put a +1/+1 counter on each Creature you control