I'm here to answer that question.
First, as annoying as flies are, you have no idea what was left on the drawing board. What if we had tiny dragons buzzing about? What if flies were poisonous? How about zombie flies that only die if you shoot them in the head?
What if spiders could fly? Imagine that - flying, carnivorous spiders. Hoo boy!
Photo: The Firefly Forest.
Second, do you have any idea at all how hard it was to create a Universe that could sustain life? Adjust any one of a bunch of cosmic constants by just a tiny bit and you get Vast Wastelands of Death. Here's a few examples of these constants:
Fine Tuning Parameters for the UniverseThe weak force had to be tuned to an incredibly fine value in order to allow life to evolve. Adjust it just a little bit either way and you get a gigantic, silent tomb of a Universe. Now you want the weak force tuned to the point where flies don't evolve? Aren't you being a bit ungrateful?
strong nuclear force constant
if larger: no hydrogen would form; atomic nuclei for most life-essential elements would be unstable; thus, no life chemistry
if smaller: no elements heavier than hydrogen would form: again, no life chemistry
weak nuclear force constant
if larger: too much hydrogen would convert to helium in big bang; hence, stars would convert too much matter into heavy elements making life chemistry impossible
if smaller: too little helium would be produced from big bang; hence, stars would convert too little matter into heavy elements making life chemistry impossible
gravitational force constant
if larger: stars would be too hot and would burn too rapidly and too unevenly for life chemistry
if smaller: stars would be too cool to ignite nuclear fusion; thus, many of the elements needed for life chemistry would never form
electromagnetic force constant
if greater: chemical bonding would be disrupted; elements more massive than boron would be unstable to fission
if lesser: chemical bonding would be insufficient for life chemistry
So that's it. It could be lots worse and just getting to the point where there are flies at all took a tremendous amount of complicated tuning of cosmic constants.
Be thankful for the flies.