For sure it's painful. I experienced that with a project we have here. It's a submission portal for students at a remote area college. Students there typically don't have reliable access to the Internet. When they go to submit their answers to their assignment, if they do not have a connection then we have to save the information locally and submit when they come online.

It's also nice because now the students can view their list of courses and assignments without having Internet. I wouldn't say there is a use case for every app that markets it but there definitely is a market for offline availability in some cases.