Hmmm.... maybe I'm just odd I guess, lol. But it does make it odd having one unit defend a base, and then watch the unit get massacred and lose that base to the enemy in one turn. Hence why 2 units is what i'd prefer. 2 units would make the base have staying power and be a way to project power.
I;m playing a game now where my citadel is outside my nearest cities firing range, right on the border of the enemies territory, yet every time Sonhai declares war, I lose the base in the 1st attack. It may be because I had a pikeman there, against crossbowmen, but it makes the citadel feel useless when it falls in the initial attack.