The concept is very simple the mobile device vendors should think about customers while designing a phone. Normally playing with phone system software sometime makes the phone useless (called brick). A phone that would never brick should follow the principles of the configurable system setup just like in PCs and allow user to configure the boot sequence into different system areas like recovery,fastboot/odin, normal and external USB ( through OTG) and in case a person overwrites his recovery partitions he can still boot by setting USB OTG as booting device and from here recovering his phone from dead to alive.
Further, from hardware point of view it should follow something like this https://en.wikipedia.org/wiki/Modular_smartphone
The advancement in computer technologies has bring revolution in our day to day lifestyle, However, these technologies has a very serious implications and violates the basic consumer rights. Before going to the discussion I will share an example of a piece of furniture. If anybody buy a wooden table he can change that table into a chair by disassembling,cutting and adding some wooden components to shape it into a chair. But as far as electronics devices this is not the case and I strongly feel that it is a violation of Human Rights as when I buy an electronic device such a smartphone It means I have paid for all the technology that devices contains including the hardware and software. But as I perceive the vendors thinks they did not sale it instead they rented it out to customer and the customer is bound to the regulations.
This phenomenon is obvious from the fact the schematics of the devices are not available at all which make it difficult for researchers and enthusiast to hack the device and find some other interesting uses cases for it. Further the worst thing is the devices are even boot locked. You cannot compile another operating system for the device. For example in case of iPhone (i would call it iStone as it is too much bounded ) consumer is forced to use only iOS (even I think for jailbreaked one also * I am not sure). For android based devices they are also boot locked and you have to root it (which I thinks voids the warranty) vendor has some proprietary (sucking) binaries and you can not change easily to a kernel of your own choice. I want that every smartphone should be allowed to boot any available OS for mobile and embedded systems.