Here are some alternate/custom Magic User moves to use if you prefer to see more spells overall. These might be available at first level, or as one advanced move, or replacing Arcane Research (with some more tweaking). Critique is welcome.
When you spend at least a few hours distilling magical potential from an arcane tome, artifact, or place of power, forget all memorized spells, roll a new spell, and memorize it. Use your name in place of “Wizard Name”.
Cast Ephermeral Spell
When you cast a spell not in your spellbook, use Cast Spell as usual, but On a 10+ you also burn the spell into your spellbook.
Lost to the Ether
When you forget an Ephermeral Spell, it is gone forever.