Whole genome sequencing is extremely useful, actually. It has immediate applications--now the beef/dairy industries will be able to breed for greater production, better health, various useful traits. They will also be able to breed for genetic diversity and avoid bottlenecks from overly-inbred animals.
After they sequenced the entire human genome, they found causes for a lot of diseases that they had previously thought were environmental; turned out they were genetic in origin, but caused by multiple gene interactions.
It's also good for telling you whether or not an animal is actively evolving certain characteristics. For example, human immune systems are actively evolving rather quickly, and we see increases in people with allergies; you hardly ever used to know anyone with an allergy, it was rare, but now seems like lots of people have allergies of some sort.