Newtwo, the issue is that novel changes in genes not previously linked to a disease have unknown significance. Every genome sequenced has at least a few HUNDRED such changes. Consequently, until there is enough evidence for a single gene, or even a single genetic variant in a gene, to allow it to be reported , it doesn't provide any medically useful information. In fact, if action were taken because of a variant of unknown significance and that variant eventually was shown not to be detrimental, the lab reporting the finding would be likely to be held accountable for damages.
That being said, the only way to discover variants that are mutations and not just polymorphisms is to do the sequencing. If you don't find unknown variants, you can't find new causal genes, but you can't report every variant you find, because there are too many. That's where big databases, no HUGE databases, or specialist companies like MYGN, become necessary.