Welcome to the wonderful world of being a Monk. "Hmmm, the monsters got DR and its stronger than me? I...um...grab a healing potion and ready an action to give it to one of the real fighters if he gets hurt." ;-) Actually, I made about 5 different puny contributions to my fight with the dragon; I was a damage sponge for some of those scary multiple attacks, I sucked up some AoOs so that other characters could maneuver more freely, I applied the Heal skill to a fallen character, I passed around Healing potions, I distracted the Dragon into using the Breath Weapon on me once. Yeah, thats about it. Oh, well, I fought for a round or two. Probably did 3 points of damage after the DR took effect. And gave that precious +2 Flank bonus to a Barbarian who was probably +11 to start. Blah.
As for the Stunning Attack debate, can you imagine how useless this ability would be if you had to give up your multiple attacks for it? As it is, its already extremely marginal due to many big monsters having a good CON and hence a good Fort save. I just throw the Stun into the mix because it is free; even though I generally expect it to fail at least it doesnt cost me anything. If I had to choose to use it instead of multiple attacks, it would never get used. Of course, "special" abilities that never get used are the Monk's forte. "Look at me, I can Deflect Arrows on a 19 or 20". Used exactly twice up to 6th level.