Roil Spout doesn’t work on tokens creatures.
I mean, it’s true that the token isn’t a card, and therefore can’t be put on top of it’s owner’s library…
But then every bounce spell in the game which returns a creature to it’s owners hand DOES work on tokens, even though they aren’t cards.
In paper Magic, token creatures count as cards or permanents when they are on the battlefield. You can send a token to another zone, such as your graveyard, your library or your hand. When it reaches that zone, then it ceases to exist.
I agree that Roil Spout does not behave as expected. I don’t know if this is intended or not. I would prefer that it could be used on token creatures, because this fixes the problem with bounce. Also, at 10 mana, it is more expensive than Disperse (4 mana), Anchor to the Aether (7 mana), and as expensive as Harbinger of the Tides (10 mana) or Baby Harbinger of the Tides (10 mana) (I forget his name). For 14 mana, you can wipe the whole board with Displacement Wave, or for 20? mana you can add a giant Octopus with Crush of Tentacles.
If you’re going to talk about balancing the mana costs of cards, then it’s probably best not to compare anything to Crush of Tentacles 