KDE was hardly ever "corporate", but it was always somewhat controlled / guided by the company behind Qt (Trolltech, originally); for the simple reason that most of the top KDE hackers were top Qt hackers and hence, in most cases, employees of Qt's owners. In many ways, getting involved with KDE was a good way to audition for a job at Trolltech/Nokia/Digia/whatever-it-is-now.
Add to it that KDE saw some significant early deployments in the European public sector, which resulted in some particular attention given to collaboration features (imap, calendaring etc). That might have looked corporate to some, but it was just a necessity for bootstrapped QT-centric businesses trying to take on the office giants like Microsoft and IBM.
I always felt KDE was more of a corporate project. It's also been my impression that KDE comes with a lot more dependencies. IMHO GTK is a decent toolkit with lower complexity - it's GNOME shell that I really don't like but I live with it.