The listed roles were just to show the idea of the service; an role providing mail and calendar (e.g. Kolab) would only have a few required options (if any). Any additional detail would be optional and have our default recommended values.
I would say there are plenty of people who _would_ be interested in that sort of a service. I've been thinking about this since I wrote the above responses, and I'm fairly certain that what I want is gmail + google calendar + google drive, without the google. The more friction or configuration steps I have to go through, the less likely I am to use it.
Case in point: I'm not particularly happy with providing LastPass with my password info. I currently pay for their service. In order to transition to KeePass, I have to give up the automatic sync functionality between my devices, I have to manually back up my key database myself, and I lose the browser extensions that lastpass provides. I'm finding it hard to justify switching for the above reasons.
The listed roles were just to show the idea of the service; an role providing mail and calendar (e.g. Kolab) would only have a few required options (if any). Any additional detail would be optional and have our default recommended values.