Why is the default the public disk?

[lostdesign]

As per "default" or something I am used to, is putting your images into the storage folder and symlinking that to the public folder. The medialibrary is putting them into the public folder right away, any particular reason why that is the case?

How would you handle private and public images, such as keeping the original private but putting a different version of it e.g. lower res public?

EDIT:
Welll seems like I should just use multiple disks, setting the visibilty for each of them and work off of that.