If secure means closed well, that is not a trade off a lot of people are not willing to make. Just take a look at the outrage from the Windows 8 secure boot loader that can theoretically stop linux from being installed.
Personally, I like it when companies include some physical mechanism of getting root access to the machine. Whether we have to get root access through the charger port, or pressing F12 when the PC is booting, this mechanism will by definition have to be a 'vulnerability.' Of course, root access in this sense is referring to bootloader root access, not the operating system - that would be bad. We can only assume which type of root access is being referred to in the hack above.
You're living inside a tech bubble. The vast majority of iPhone owners don't care about "open". They care about "it works". These people are benefited greatly from having a "closed" yet secure system.
Don't use an iPhone :) Vote with your wallet! And for the Windows 8 lock down of Linux, there are still numerous ways to get a Linux-enabled laptop, or to ensure that what you buy will work well.
And you can. Visit http://forecast.io from iOS Safari and add the icon to your home screen, then run that.
This is the app distribution method Jobs tried to sell developers on. Developers mostly don't want want it.
Of course, you can also run your literally own apps, native apps, by installing them yourself. You only need the App Store to sell them.
Finally, you can set up your own distribution platform. See TestFlight.
