via MacObserver:
This change will generally go unnoticed by most average users except for the absence of that button in /Applications > Utilities > Disk Utility.app. A revised, better looking and easier to understand version of Disk Utility comes with El Capitan. However, in some cases, there could be further impact.
I tried to repair disk permissions over the weekend and noticed I couldn’t. This explains the situation. If the Mac OS handles all of the maintenance itself, I’m okay with that.