Personally, I think three is fine. That said, IMHO we also need class spell lists. No one wants to sort through in character creation going by the individual school. Especially players using the physical books. Books that WotC is still going to want to sell. Make Arcane, Divine and Primal a Tag, example; Magic Missile, 1st level Evocation, Vocal, Somatic, Arcane. If every caster got the whole Arcane list or in the case of the Bard, the chance to cherry pick every list and change what they pick, it takes space to shine away from other classes, and if everyone knows every spell, what is the benefit of being the Wizard? Up to now, the ability to learn new spells outside of level ups. And if every enemy is potentially the Ranger's favored enemy, then why wouldn't anyone who wants to fight against a backstory enemy choose Ranger or a 1 level dip?