I’ve seen firsthand the amount of work that goes into building a complex, scalable system and the problem with your statements are that 1) It’s hard to measure at scale what each of your users cares about. This is especially true with “lightweight” interfaces - simpler UI means you have to carefully decide what you want to expose. 2) Generally the older software is, the more bloated it becomes - this is inescapable. The only real solution to this problem is full rewrites which rarely happen because they’re so expensive and time-consuming. By the time you ship an OS it might already have some bloat. 3) People like what they are used to. Remember the backlash with the Metro interface? Windows users would never get behind a major change to the Windows UI - everyone has been using it for almost 20 years now.