First, you get two one-one Creatures right off the bat, which can help attack the Battle down themselves
Spider Spawning just doesn't suffer from these problems in the same way that a card like (the admittedly bonkers) Olivia Voldaren does
If you have a deck thats low mana outlets, and you find yourself having mana open often, then maybe Soothsaying is the right card for you
There are plenty of other mass bounce spells in blue, but very few ways to deal with a convoluted board state, especially in as permanent a way as exiling all creatures like Oversimplify does
Another exploit for creature tutors are combos
First strike keeps it relevant in combat, and it works wonders with blink cards like Ephemerate or recursion engines like Sun Titan