Branding is one of the more important aspects of business to business application development. In specific, nothing is more powerful then walking into a business meeting with a client whom you are trying to sell you application to; then showing them a completely redesigned application -- specifically the way they would want it to look (their assets, logos, color pallete, etc). Whether its a mobile app (iOS, Android, whatever), or desktop application -- personalizing an application can make the difference between landing a deal versus having the client walk out the door. It makes it "their" experience rather than your own.
While branding isn't necessarily used and/or useful for every application -- I believe a great deal of applications can benefit from basic branding. After all, "branding" is just another way of saying "personalization"...and who doesn't like to personalize an application to their tastes.