I find that many of the Expert exclusives are a bit of disappointment. They're so limited in how they're used. That includes the Brain of Confusion, since not many enemies are affected and it requires getting hit, as previously pointed out.
In a way, changing it to a Brain of Knowledge for spellbooks keeps its limited functionality. That would be somewhat of a disappointment for non-mage players in an Expert Crimson world. To further what
@TMB50 said before, a Brain of Knowledge could provide an attack or critical hit boost, making it the offensive counterpart to the Worm Scarf's defense. This comes about from the Brain analysing enemies to identify their attack patterns and weak spots. (Not literally, but just within the game's lore.)
Aside: An information Brain giving effect of multiple potions is an expert exclusive drop I wanted from the Twins.