And also if you ever need to access anything on-the-go, you either can't or have to keep the notebook with you and make it susceptible to the things you mentioned + theft or snooping.

I use a copy machine to back up my password list. The pages go in my fire safe with other important papers, and a second copy off-site.

I guess you could just take pictures of the pages and save them to a thumbdrive or an SDcard, but I prefer the lower-tech solution.