The problem with subtle is potentially the visual clues on opponents.
Not to say that one shouldn't strive for a balance.
But visual feedback still works even if it's not on all the time. E.g. someone has Fire Resistance / Protection from Elements or such on (whatever it is in 5e). You hit them with a fire attack and energy flashes and absorbs the fire. That would actually be
more clear than having some sparks flying 24/7 that don't even react to fire (like NWN).
But the absolute worst is when you spend a lot of time customizing the look of your Wizard, only for them to be a sparkling pulsating force bubble mess 24/7 and you can't even see the character model anymore.
How come NPC's don't react to that obscuring mess during dialogue?
I'm not sure all magical protections even
should be visualized. A big part of the usefulness of a protection spell is that your enemies
don't know about it. If they do, they can always choose to target another party member who doesn't have it. And this should work both ways.
Maybe even give Detect Magic a purpose, revealing those auras and protections?