Add the feature to import .ics, .olm and other calendar file types instead of forcing users to connect their actual accounts with your app.
It would be really nice to be able import calendars instead of having to fork over account names and passwords. There are specific calendars from each service that I want to track with this app but I am unable to simply import an .ics or .olm file. Being a third-party app, this makes me leery about security.