Dano, I couldn't AGREE MORE,on your second to last paragraph from you post, thank you truly, for making the statement!
The drawing you refer to.... "the stately chap and cane pole carrying boy", is a Norman Rockwell, actually and was first commissioned by Outdoor Life many many moons ago. I still love it, when I see it!
This same piece of "art", I've also seen redone in more "cartoon form" in various publications, with wording added to it, to the effect of "Young fellow, how would you like to fish with my "EXPENSIVE CANE ROD, here? Just because I'm a "fine outdoordsman", son, I'd be willing to sacrifice a bit of my fishing, in order to make the trade of gear with you for say...................an hour or two?"
As to, the "exact imitation of insects", boiling down to one of our sport's oldest and worn out, slogans, "Match The Hatch", I think, no, I KNOW, I'd give up this sport/religion/obsession/mental illness, I so dearly love, IF I couldn't "make up my OWN fly patterns","experiment with new materials", and generally "fly fish the way I want to fly fish", because I had to 'stick to a regimental set of rules", concerning correct fly construction!
Of course, like we all do, to some extent........ I'm not going to use a black ant, if the caddis flies are coming off the water like snow flakes. But, still, the fly I tie on, will be of my OWN design and probably not even close to resembling the actual insect.
If all of this; "match the hatch, as absolutely close as you're able to imitate the natural" I highly doubt, then, that the Royal Coachman, would have remained such a fine fish catcher all these years!?!
I may carry a lot of fly boxes with me, on the water every trip, but I DON'T carry a lot of different PATTERNS.