Complaints are bad, simple. Not only do they consume time, it also means we are spending extra time and resource for a piece of work that was already supposed to be "finished" (apart from further damage that can come from word of mouth). We know from experience that no matter how big a corporation is, the customer service can only go so far in satisfying the customers. But if very high number of your customers are usually satisfied, then it is safe to say that you can keep your business running (at least for now haha).
With Internet and social media in everybody's lives, customer complaints about businesses are reaching far audience and new searchers who are looking for information on the Internet. These complaints reach people through review sites, complaint boards, public forums, rating sites, social media sites, blogs and various other ways people share their experience (Google, yelp, facebook and twitter being the biggest playgrounds). It is impossible to deal with them on a daily basis, and it is more so difficult to control because of the freedom of speech on the Internet (well that could well be gone if SOPA and PIPA are passed!). Bottom line--more people read about a business online now a days, and if your customers are talking about you on Internet, you might be losing business just because of that. It is not a joke, a single click of a button with a unhappy client can put your entire sales staff look stupid!
So if 80% of those complaints are coming from 20% of the customers, and assuming some of the complaints aren't really truthful, how do you handle them especially when you know a lot of them have no ground? There is always a chance that competition might have a role to play in this, but do you hire somebody to monitor and analyze this? (It would be another topic to discuss how are the reputation management companies faring in that department--do all of those really have the skill set needed to monitor and analyze?). What other factors are responsible for consumer complaints? Are businesses measuring the severity of the complaints(later "damage" if reproduced online or via word of mouth), so that the impact of the complaints can be minmized to improve business.