How can I stop iOS updates from downloading automatically via Wi-Fi, on my iPhone 6s with iOS 9.0.2? This may be more of a question on what Ask Different community thinks of me than a technical question on iOS 9 updates.

Thanks to Alex Malcoci here, now I know how to stop the reminder about iOS update installation from popping up every day on my iPhone 6s with iOS 9.0.2. Also thanks to bmike on the same post, now I know that Apple doesn't provide users an option to turn off automatic download of iOS updates on devices with iOS upper than 9.x.x. I also learned from another post on Ask Different that I can, despite bmike's advice above, turn off automatic download of updates via mobile data.

So, the only problem left for me is the automatic download of iOS updates, which contain features and fixes that are most of times totally unnecessary and irrelevant for me, via Wi-Fi connection. As a sensible way to cut down my mobile data use, I leave my iPhone 6s connected to Wi-Fi at my house and disconnected from mobile data, whenever I'm home. I don't have problem with the storage space on my iPhone even if updates are downloaded automatically via Wi-Fi, since I still have about 20GB left empty on my device.

But still, I want to stop automatic download of iOS updates via Wi-Fi connection, and be able to choose which update to download and install. This is absolutely a matter of like or dislike, and not something that's causing difficulty or annoyance on use of my phone. So far.

Am I a social outcast who wishes to take control of what's downloaded to my device by resisting Apple's forced download policy, and who also deserves to stop living with Apple devices, if I dislike so much the automatic download? Which is more crazy, me disliking or Apple forcing?
Apple isn't 'forcing' downloads on you, but instead is making it convenient and easy to stay up to date on Apple software. That may sound like a spin on the point of view, but Apple doesn't want you on the latest release so they can crow to the press about update percentages.

They do this for at least two reasons: 1) it reduces their support costs, as customers migrate off older code, and 2) it provides critical security updates and bug fixes that may put your device and data at risk. 

Apple does drop support for older OS (if you have an original iPad, you know it is 'stuck' on iOS 5).

Automatic download of the updates does not mean that you are forced to take the update, it just means the update package has been downloaded to your device. Installation is still something you must approve, and kickoff. The phone will not update the OS without your input. 

You won't suffer from new features or anything in the new updates until you apply them, so other than using some storage space, there is no downside to having it downloaded in the background.

Something to consider: Apple includes many security updates within its OS updates, most of which are (sadly) not well documented in the update notice. skipping these updates may put your device, and data, at risk.