Well, you are right and wrong, depending on how you inserted the document
into ON. If you use the Print to Onenote printer, it goes in as an image,
and you can highlight, notate, etc, but you can't select the text itself
directly. You can right click on that image-page and Copy text on that Page
to be inserted into a document or edited.
You could also put text, not images into Onenote, then work directly with
the text from there. Just simple copy-and-paste from the other editor (Word,
Adobe, etc) and paste into ON.
I think, however, that you aren't quite understanding ON quite yet. It's
not a Word processor- it's a notebook. Work on your Word documents in Word;
if you need to edit PDFs use Adobe or something like PDF Annotator. ON is a
notetaking tool- put all your notes in ON, scans of your bills,
self-references from your emails, clips from the web, etc. They are
searchable, indexed, you can hyperlink between pages and sections, you can
email them, and you can create shared notebooks to collaborate with others.
It's different than Word and used for a completely different purpose.
I did my MBA with a tablet PC and Onenote. Most valuable thing I ever did-
once you understand it, you can have Onenote "study groups" with multiple
people working at the same time on the same document and watch - in real
time- as people add images, charts, and notes. I've graduated, but if I need
to look up something from an old class, I just open my School Notebook and
can search through every single handout I ever got, my handwritten notes, and
even the spoken speech of the lectures I recorded. It's a beautiful thing.
I recommend you get to know ON- you'll find it very helpful when you do.