This is something that should have been done updates and updates ago.
A Couple of things that would benefit from this:
i) People can see who is online and if they are high enough can ask for more powerful troop requests
ii) If you want opinions or questions you can ask who you know to be a 'vet' at the game so you can get accurate answers.
iii) When offline (If you have a bar which states "Online X hours/days ago") Elders or Leaders can determine whether they want to kick someone who may have stopped playing the game altogether.