An appropriate degree of freedom is different for you and eight year old children or grandparents. The majority of iOS users have no use for the freedom jailbreakers desire and Apple is creating software for the majority of its customers.
That's not quite true.
There's a bunch of minor tweaks that many people would really like that they can only get if they jail break. Since most people are scared of jailbreaking they don't do it.
It's hard to understand how different keyboards[1] is inappropriate degree of software freedom.
[1] to pick one example of a simple, minor, tweak that many people want.
"[1] to pick one example of a simple, minor, tweak that many people want."
Agree with your point except calling it a "minor tweak". From personal experience, the difference between the stock iOS keyboard and something like Swype on Android is huge. This third party keyboard on Android was so popular and influential that Google finally added swype like functionality in the base OS (I think starting with JB). This is one of the biggest frustrations I have with the iOS experience (whenever I do use iOS, e.g. on my iPad).
If you're not satisfied by those restrictions, use Android. (I do, because I'm not.)
If that is not enough, the unlocking process can be as complicated as needed to discourage careless unlocking. Most people, when asked, e.g., to convert a decimal to a hexadecimal or to engage their frontal lobes in some other way, stop being careless.
Remember that the only point I'm trying to make is that it is not strictly necessary for Apple to do their best to keep motivated technical users from escaping their "jail" to prevent kids and grandmothers from harming themselves.
And does anyone actually believe that protecting naive users is the only reason Apple makes it as hard as possible to jailbreak iOS?
I wish I had your circle of non-technical folks. I've been called (from other people's phones, no less) numerous times asking why data doesn't work (they deleted all the APNs from an Android phone), why their picture messages don't go through (they changed the MMSC URL to their homepage), why voicemails stopped (they set the voicemail service number to their own number), and several more. Changeable settings are like mountains; they're messed with because they are there.
It raises support costs, and frustrates the vast majority of customers.