It really comes down to standards. The rest of the industry uses a set standard to share contact data and pictures. Contacts are shared via vCard files and I'm not sure what is used to transfer pictures but it is an industry standard.
Leave it up to Apple to decide to do everything differently and to make their devices incompatible with everyone else. That's really the whole point of their all-encompassing ecosystem, to keep you locked in. Suffice it to say, that's why I don't like Apple. I don't agree with their "it's our way or the highway" mentality.