In my opinion, there's a lot more to it than "fish meets standards or not." As a breeder, you end up with a batch of fry that will grow into adults. As adults, they need to either be sold or given away. Realistically, only a small percent of people you know will willingly take a betta from you because they'd need a tank, food, and keep up maintenance which is both money and time. The fish may end up sitting in a freezing, dirty bowl somewhere, flushed, fed to something bigger or simply forgotten about. Aiming for higher quality fish means other breeders (who are serious about the care of their fish) will actually be willing to purchase the fish, not only because they have decent form, but because you know the genetic history it. Pet store fish are meant to be exactly that- pets. If money is an issue when buying a pair to breed, then being able to afford the whole setup and maintenance of the spawning process is far from your reach.
It's vitally the same as deciding to let your neighbor's chihuahua mate with your mini poodle. The pups will be undesireable, the genetics scrambled like a rubix cube, and you've only added to the number of homeless, unwanted pets in the world.
This is in my own opinion, of course.