@manoiese
As @AppLee said you don't sound rude, just honest.
But what you don't understand is that Ubuntu Touch is like that since the beginning, Canonical made it that way (read only in first) and users like me that adopted it since that time don't need a phone system with full access all the time.
Like already said if you want you can make it full read/write in a persistent way.
Or like you experimented, temporarily untill next reboot.
That can be useful, but for normal users for whom the system is designed, again, since the beginning, it is not mandatory or a normal use case.
If you want to continue with Ubuntu Touch on a normal way, you should consider trying to achieve what you want/need in respect with this particular behaviour of the system, like some Devs already did with crackle or things like that, I'm sure this would be a welcomed contribution.
Or maybe, like said @AppLee also, Ubuntu Touch is not what you need.