So in general for spells that have no benefit from casting using higher level spell slot UI should not any allow choice (autopick level 1 slot for Mage Armor) and probably warn you if you don't have a slot of the lowest possible level.
considering what a mess the UI is right now any change in this regard would be welcome, and expected. Having a separate button for each spell level in madness.
But that's something for 'Feedback' I think
