You just examplified my point, 90% of these features are not required by the average user, only geeks/nerds care about it.
Back button, haptic feedback, and UI modifications are also mostly personal taste. I've switched from Android and I don't miss that anymore, iOS's simplicity made me realize how a lot of gimmicks in Touchwiz are just pointless, felt like bloatware made by samsung.
Native Google Apps, well thats also matter of taste, but I think some google apps on iOS are much better than some on Android like the Gmail app for iOS which I think is more fluid than the android version.
SD expansion most people dont care, In my circle of friends most of them use Android phones and very few bothered to use an SD card. Unless you are data hungry you won't care about it.
4K video recording, thats not something great unless you rely heavily on Video recording. the majority of people wont care about it. Most people dont even know what 1080p is... This is just for geeks or people that has some knowledge on video editing IMO
Replaceabe battery, thats personal taste. Some people love it, others don't care. its very convenient for the heavy user. I dont miss that feature very much because i find my iphone 6 tremendously power efficient, 1800 mAh that can last for 5-6 hours on very heavy usage, or surpass more than 10 hours with light usage. My old Galaxy S4 had an 2600 mAh battery and it couldn't last as long as my 6.
RAM, other thing only geeks and nerds care about. The vast majority of users dont even know what RAM is... So its pretty pointless for common users... I dont see that much difference between 3GB of Ram on the note 4 versus 1GB on my 6. iOS does an fantastic job on memory optimization, everything is very fluid when I use this phone. You may say "oh but look at that constant safari tab refreshing" yeah it would be better If it didnt happen, but for me it only takes less than a second or so to reload, so it doesn't botter me that much.
AMOLED screen, again, only geeks and nerds will notice any difference. I dont care much about it, since my previous S4 sucked so bad at brightness levels, I find the 6's screen very useful on this aspect. And on the colors/contrast stuff I also dont care about it, I dont use my 6 for viewing movies and stuff, thats why I have an HDTV for.