Premium domain names give customers a great sense of trust and authority. Users will, for instance, have significantly more trust in doing business with www.cars.com versus www.find-cars.us. This gained trust is mostly due to the fact that today’s online consumers generally understand domains like cars.com are rare and valuable; and that fly-by-night operations are certainly not run on such a property. This trust and authority directly influence users purchase decisions leading to higher conversion rates. In other words, you are buying credibility and don't have to establish your business nearly as "manually".
Today, a strong web presence is more than a must-have for a company: it's a "must-leverage". Since a customer's experience with virtually every company he or she does business with now centers on web interaction, your company's online presence isn't just an extension of your "real" presence -- it is your presence. The foundation upon which all of this is built is your domain name.
Premium domains heavily market themselves on their own and can make up for a lot of money spent on normal marketing that may or may not even work well (and those investments certainly can't ever be resold if things don't work out). Reason being is these digital assets work around to clock to influence users to ultimately do business with you; this is mainly done via shaping a positive user perception of you (which will lead to business), and also helping them retain this perception (future business). Consumers want to spend money & do business, make it easy to decide who to do it with.
If your company name is Kite, and you operate on kite.com, that can prevent some negative things. Not operating on your corresponding .com leaves it open to: someone else operating on a domain you should own, confusion for potential customers looking for you, missed traffic, forcing you to settle for a lower quality domain, and ultimately limiting the level of presence you can achieve for your brand online.