Hi Sagai,
The question stems from what the intended purpose of DI/DO is. In otherwords, not just to fulfill ISO13485 requirements, but to actually have a document that traces design decisions in a meaningful way.
Basically, I'm just proposing a modified DI/DO document format that actually traces how outputs from one stage of the design process feed into the next stage's inputs (rather than just have the initial inputs, and final outputs as would be in a typical DI/DO doc).
To me, this would be a much more meaningful design document...