Why was the old KDE menu replaced by Kickoff?
The traditional application starting menu from KDE3 had various usability issues. First and foremost, people tend to use no more than 6-10 applications regularly. Having those applications buried in deep menu structures makes it a lot of effort to start them. Those favourite applications can with Kickoff be moved into their own tab so they’re easilly accessible. Kickoff might, for new users be more complicated to use since the “browsing applications” usecase has a less central position. For mid- to long-term users, Kickoff will increase productivity for the most common cases. For users who prefer the traditional application launcher menu, it can easily be changed by right-clicking on the Kickoff button and choosing “Switch to Classic Menu Style”.