Why is it a bad thing that breeders work with genetic lines selected by other breeders? It takes a whole lot more work than just crossing two plants to make some seeds, but even that isn't all that bad if you select a good, strong male to pollinate with. Years of experience and generations of test crosses and selections go into creating a strain. Using landrace strains is a great way to bring new genetics into the gene pool, but recombining the alleles of existing strains can bring out some incredible traits. Your f1 hybrids are probably exhibiting hybrid vigor.