unless if you allow users to root, like providing spft firmware, then we can unlock the full potential of an ANDROID phone.
android is not meant for locking everything like the iOS (like what you are trying on FP2).
rooting itself doesnt result instability like what bakar is mentioning. it is user's responsibility. but rooting is a great priviledge for those who are knowledgable for what it is meant for.
its like you are selling your FP2 for users who are just like for texting and calling (and cost cutted camera). too bad, this is android. and android is known for customizations that we cant see on iOS or other platforms.
discouraging 3rd party devs with your device because you are not providing tools/softwares/codes will make the device stuck in its state forever. like those unsupported devices (mostly local brands). admit it, your devs cant support an old device forever. you will always focus on new releases. so releasing needed softwares will help 3rd party devs to continually support a soon to be forgotten device.
just my 2 cents.
(and oh, stock software itself is a bit unstable. refer to the "stock firmware thread" in this category by @apfotomsg. internal storage is considered as zRAM instead of MMC? laggy file manager, messaging, and phone apps? rooting may potentially fix these. )