Another Idea:
Allow Rangers to Detect Traps and disarm them... I mean they are mean to be "scouts" - Let them scout out danger.
Different from thieves? Yes - can't open locks or detect illusion (or maybe let them detect illusion - they should be masters of seeing things out of the ordinary like following scant tracks hardly able to be seen normally.
I usually create a thief dual to mage in BG due to this: I like to be able to detect, disarm traps, and open locks with my main character, and mages with their spells need more micromanaging, so being a mage thief means I don't have to switch characters back and forth all the time.
I wonder how Larian will handle these sort of things.