I have a couple of issues with your post. One is the assumption that a lesser quality foal will be lesser quality in a way that makes it “perfect for a non-pro”. I think most WB breeds (much less TBs, Arabs, ASBs, even Morgans!) are being bred spicier because it takes some spice/self motivation to get to the upper levels. BUT, if the talent doesn’t match the spice, where does that horse go? Now you have a less talented but hot horse in the hands of an ammy that wants to toodle around. Or can only ride 3 days per week because they work 3 jobs to pay for these ridiculous animals. Not a good match, IMHO.
You also speak of perfection as if it’s objective and as a dressage rider, I know that is just not the case. You mention dog breeding - look at Old English Bulldogs. These dogs, in the name of perfection, now can’t breathe, can’t poop, can’t have babies, without human intervention. Many have skin issues and food allergies to boot. But they were selectively bred to look a certain way and with those extremes come other, non-desirable traits.
I don’t think it’s as black and white as you hope it would be. I think perfection lies in what your goals are and what you enjoy.