ios 10 vs 11

I am kind of like you and need a good reason to upgrade before I will. Security is a black box so it is hard to judge it. I have never run a current operating system and nothing bad has ever happened to me. Mind you I have nothing worth stealing either so maybe I don't sweat it. New iOS version have a few more apps but if you don't need them then why bother. There's bug fixes but then there's always new bugs with those fixes. One thing to keep in mind is that should you ever need to recover your phone you're going to get the new iOS whether you like it or not.

I guess the main reason to upgrade iOS is even if you run old apps, new versions will appear that may require the new iOS, or you may want a non-Apple app which does. It's tricky finding anything for iOS9 on the App Store these days and iO10 is next in line.

I agree with Carolyn on this. The security updates in iOS 11 have been significant. If your device supports iOS 11, you should be using the most recent version.

Here's a little light reading:

About speculative execution vulnerabilities in ARM-based and Intel CPUs - Apple Support

Apple security updates - Apple Support

If you have a relatively recent device, you're not likely to see a performance hit. There was a temporary hit when updating to iOS 11 because of a change in file structure. For the vast majority of people, this was something that lasted for about twenty-four hours after updating while the system finished up the background tasks.

I understand that the security patches were tested and show to have insignificant impact,

My understanding is that wasn't the case at all. There was a feature built into iOS 11.2 ( I think) that does, under some conditions, throttle iPhones that have failing batteries. This is to prevent total shut down. It's also easily resolved by replacing the failing battery. It does not apply to iPads. I have the latest version of iOS 11 on both my iPhone 7+ and my iPad Pro 9.7. Other than the aforementioned issue the day or so after updating, I've experienced no changes in performance.

I'm not sure what you mean by "every iOS release seems to try to force me to use products like apple maps and Photos". They are both iOS apps but, not only do you not have to use them, you can even delete them if you don't like them.

Remove built-in Apple apps from the Home screen on your iOS 10 device or Apple Watch - Apple Support

missing something?

Yes. Security.