Uploading images directly onto the server takes up a lot of resources and space that we only have a limited amount of to spare for normal users without compromising vital functions of the forum itself. You need to have a lot of space for storing stuff (especially since bigger pictures can actually be pretty big and use up a lot of available space en masse) and that always costs. I have no idea what the actual capabilities of our server are and to what extent we could think to spare personal space for users in the way that you have suggested, but for the simple fact that the option has been disabled thus far I'm inclined to believe that it is not very possible, nor will it ever be.
This is all mere speculation, of course, and we would need an admin to further explain the situation, but I think it's safe to say that we cannot transform into an upload service. Not with the size of our userbase.