As the saying goes....you can always sell a race horse, but you can't always race a sale horse.
So, if you are a smart breeder and you breed to sell, you certainly try to pick what will be commercially appealing but you always pick stallions that complement and improve your mares.
If any little thing goes wrong on the way to the sale, and about a million things try to wreck the horse before you get there, and you have to race the horse to sell it then it certainly is in your best interest to breed a runner.
I think it is a fallacy that great conformation equals great performance and soundness. Racehorses get sore not because they are poorly conformed but because of their job description. They are professional athletes regularly pushed to their maximum level and it results in wear and tear.
I'd always heard the blather about the Warmblood breeding program and how superior it was to our way and then I went to work for some folks who had Grand Prix jumpers. These are folks with lots of disposable income who can afford to buy nice horses, and lets just say that from what I saw first hand the Warmblood folks breed a lot of crappy horses that are poorly conformed and they end up in the US jumping over small fences, just like out cheap claimers.
Personally, if I am going to get a lecture on how to improve the breed, it would mean more if it came from someone who actually bred TB's and didn't just read about it in a book or on a message board. I doubt someone with real experience would say some of the things that were said here or make those claims because the reality of breeding is much different than the theory of breeding a better horse.