In my early years of flyfishing I was dry fly only. Nymphs were beyond me - I didn't understand them or how to fish them. I could see a dry and most of the time know I was matching the hatch and most certainly know when I had fooled one.
Now I catch most of my trout on nymphs. I almost never use wets or streamers. In a heartbeat I will switch to dries if I think it'll work. Often times I've had fish hit my indicator and I'll switch to some outrageous looking dry and frequently fool a few fish before going back to the nymph.
I could never just sit on the bank waiting for a hatch to happen.