Defend does have strategic value depending on how it is used. Your right in believing that doing nothing but defending is pointless, but when enemies have hard hitting attacks defend can save your life. In most RPGs enemies will announce their super attacks the previous round either by wasting the round "gathering power" or doing some weak attack that ment to foreshadow it.
If you want to incorporate a defend command, by all means do so. It is your game after all. If you want people to use it though the I would suggest that you follow the above tactic. You don't have to make it obvious in your boss fights, just make it so that people who pay attention to the fight will benefit from using defend.
Also with defend you have to make it worth using, but don't make it so that the characters are completely invincible while defending. Its a bit of a balancing act. The increase in physical and magical defense in most games is between 1.5x to double its normal value when using the defend command. This is usually enough to save your hide with super attacks but lets the player know when they are in over their heads when they have to defend constantly to stay alive.
Prome
I dont know
Johnnybdesign
Me neither :/