I had the same thinking. I think Microsoft OneNote is the example to follow in mobile. Microsoft had tried to port it to mobile devices but that is not the real desktop OneNote.
Back in the iPhone 2g era I was developing a personal wiki with a WYSIWYG UI but I stopped because I needed to use a lot of hidden UITextView/WebView object methods that were not approved by Apple policies or write my own editor engine. Many years later I don't see this kind of wiki in the App Store (no, it's not EverNote).
Amen! I've run desktop wikis, Evernote, OneNote, plain text files, Markdown files, Workflowy, Delicious, Diigo and more, and not fit exactly. Evernote is so easy to dump things into (esp web page clippings) and oh-so-hard to find/retrieve information. I've come to the conclusion tags don't cut it, as vocab I used 4+ years ago may have changed by now - heck even terms I used 3 weeks ago change as my knowledge improves.
A wiki with structure, like the Leo Literate Programming Editor used IIRC has come closest. But the space of PIM is ripe for a killer product that takes semi-structured data and allows us to run with it.
Filemaker for the web, with a bit more flexibility.
Back in the iPhone 2g era I was developing a personal wiki with a WYSIWYG UI but I stopped because I needed to use a lot of hidden UITextView/WebView object methods that were not approved by Apple policies or write my own editor engine. Many years later I don't see this kind of wiki in the App Store (no, it's not EverNote).