Seems you haven't understood the Apple world. You get fancy designs. You loose your freedom to install what you want. They decide, not you. That's the deal. Live with it or don't buy their products. (I choose the latter.)
I think you don't understand it either. While I do "lose the freedom to install what I want" (outside of the 1.5 millions apps that I can install that is), I get more than "fancy designs".
I get a system where progress and adoption is faster, I get far less (close to statistical noise) malware compared to Android (none, actually, if I stick to top tier apps -- whereas there are Android phones that came with malware pre-installed by the carrier), I get most pro apps first and often (e.g. for music creation apps) exclusively, and a whole ecosystem that works admirably well, from laptop to watch, and, for my uses, better hardware.
Sure, the OPs point was stated somewhat flippantly but the point still stands. If an average user owns an Apple device, they cannot install apps that are not on the App Store. Talking about what apps are available just seems like clouding the issue.
The answer is quite simple, many people don't want or need any other apps than those in the App Store. Most people are not developers or computer nerds.
And what they get in return is for example an (almost) malware free device.
I'll probably get downvoted for saying this...
Anyway here's an example, Google them, all reports show the same results:
> "Kaspersky Lab experts estimate that 98.05% of all existing mobile malware targets the users of Android devices."
http://media.kaspersky.com/pdf/Kaspersky-Lab-KSN-Report-mobi...
And the majority of Android users does not install applications outside from Google Play Store either, and the lastest malwares that appeared for Android are from places outside Google Play Store. So where is the point?
If the user jailbreak (iOS)/allow external applications (Android), they increase the chances of malware simple of the fact that there is nothing Apple/Google can do outside App Store/Google Play Store. If they don't, the chance is reduced by far (however it is not 0, there is cases of malwares in both App Store/Google Play Store; the most recent case was in App Store btw).
f.lux seems to be an exception to this. I'm not sure if you're right in saying that "only developers or computer nerds" want to install apps other than those in the App Store.
It's a delicate balance between security and freedom, and I imagine that it is something that Apple and other device makers juggle constantly. In this case, it means slower adoption of certain kinds of functionality. Like you say, it's something you get to live with, which I do as I use Apple products.
You have a freedom to install what you want by jailbreaking it.
Its not about not allowing users to install f.lux, it's about not allowing developers to use development practices that are not approved by Apple, common - authors of f.lux are clearly doing something that is not allowed under iOS development terms and they want to change this rules just for them and let other developers use unapproved techniques which might cause security concerns for non technical users who are majority of the user base on iOS?
I get a system where progress and adoption is faster, I get far less (close to statistical noise) malware compared to Android (none, actually, if I stick to top tier apps -- whereas there are Android phones that came with malware pre-installed by the carrier), I get most pro apps first and often (e.g. for music creation apps) exclusively, and a whole ecosystem that works admirably well, from laptop to watch, and, for my uses, better hardware.