Well there are a few things.
1. Most Home Users and Small Businesses are unable to maintain and administer their own computer. Many of the big security problems and hacks come from the users lack to properly Admin their home PC. This lack of Administration skills put Microsoft in a worse light than it deserved. Because they fixed the problems quickly and offer fixes. But too many users just didn't want to waste the time keeping their system operational.
2. People no longer want to pay a lot for computers. 1980s $4k was a reasonable price for a good PC. 1990s it was 2k, 2000s 1k, 2010s $500 Price is going down while inflation is going up and the cost. We are getting cheaper computers. Gone are the solid steel cases, mechanical keyboards, with components that were suppose to last for decades. We are cheap plastic, flimsy membrane squishy keys, and components that will last you 2 or 3 years if you are lucky. Because of this the OS cannot sell for more than the cost of the hardware. So Microsoft is doing these control things to keep cost down.
3. Because of the cheaper hardware much of the extra processing needs have moved to "the cloud". Being that many of the OS Components are on the cloud if you disable it. You will suffer performance and feature hit.
If we can get people willing to spend $2k for a desktop PC and $300 for the OS, I wouldn't expect Windows or OS X to become more power user friendly.