The distinction between touch and deflection IS a nuance that 5e is lacking, and the surprise mechanic as it was conceived for release, along with advantage and disadvantage didn't really manage to recapture that fully. I'd like it if future systems had a clean and simple way of distinguishing avoidance or deflection, for effects that only need to touch the target to take effect.
The trouble with it in 3rd was that the distinction left us with multiple AC values, derived off different combinations of attributes (Your full AC is X (Armour value + dex, to a max determined by the armour), You Flat-Foot AC is Y (Armour value, no Dex), and your Touch AC is Z (Dex, but no armour value), and whether other elements applied to various versions of your Ac could sometimes become confusing - we had a dozen different 'types' of armour class bonus, and some stacked and others didn't, some applied to all Ac calculations, others applied only to full and flat-foot, others applied only to full and touch... and so on. This was, overall... too complex for 5e philosophy. I'd like it if a way could be found to preserve that nuance, but keep the understanding and calculation of it simple.
