That's great news Bernard.
It was to increase security, added back in Vista SP2, so that elevated programs could not run at startup with full access to everything. Since you would have to manually add a elevated program as a task with UAC permission to open Task Scheduler, it is allowed to run at startup using this method. A malware program, for example, could add itself automatically to the normal startup programs list with no permission from you needed and have full controll over the computer the next time you started/restarted the computer without this security feature.
It's a bit more work to make elevated programs to run at startup with this security feature, but we'll be a lot more secured for it.