I do things in my house too infrequently that I don't want to have to re-learn the UI of a tool again and again.
But maybe I'm not the target audience.
You might actually be able to get away with less structure and just dumps thoughts and ideas, statuses, and documents into $AI and have it generate ad-hoc reports.
In which case, a text file might be the right interface.
Kind of a non-answer, I realize.
I suppose the answer is: because I had a relatively specific idea of what I wanted to build and I didn't consider not building it.