A basic file repository like they ALREADY DO with photos is much simpler than the convoluted sandbox system in place now. If your saying that adding an attachment when replying to an existing email is too complicated, then ios is truely for grandmothers only.
Even with this, iOS still feels like grandmother OS for me. I really wish there is a centralized place for us to store all downloaded files, attachments etc.
By the way, Apple could probably never do a file repository, it just against their ideology. I am going to keep my jailbreak as long as I could for iFiles