That's a good point and I think you're right. I know personally bookmarks are easily put into three categories:

* Sites I visit often and don't want to have to type to access

* Things I found and want to read (or reread) in the future

* and finally pictures or funny things I want to be able to share or look at later. So almost the same as #2.

For for items 2 & 3 offline access would be a great feature.