Here's a little thought, inspired by the post on GROGNARDIA about ability scores. We all know by now that Intelligence in Men & Magic has only one effect: a modifier to experience earned for Magic-Users. And the Greyhawk supplement added a table giving the percentage chance of knowing a spell, and the maximum number of spells learnable, for different intelligence ranges. Again, these only apply to Magic-Users.
What if they only applied to non-Magic-Users?
What if a Magic-User could learn any spell, as many spells as desired, but non-Magic-Users could only learn a handful, and needed a roll to successfully learn a spell... but they *could* learn a spell, in contrast to the default assumption?