I do not understand, every wizard earns their spells from their school. By demonstrating their knowledge in battle and by finishing quests they earn experience points and level up starting with basic useful spells and eventually getting stonger spells. Along the way you learn to attack, shield, heal, set traps, use bonuses, and work with others. without the small spells you would lose more often.
Would you have enough pips if you could just choose? As a Fire grand I would know. You earn your spells as the higher your level gets. Higher rank spells use more pips, more pips to use means more passing turns and that means more health gone! And earning spells happens for every school not just myth!