I think we need to ask ourselves whether providing the mechanism, markup or specification for which version of an image to load in order to maintain one and the

I think we need to ask ourselves whether providing the mechanism, markup or specification for which version of an image to load in order to maintain one and the same INTENT across clients should be the responsibility of front end developers/designers? In my opinion, the only work the designer should have to do it to declare a particular image should be displayed. It should be the client<->server's responsibility to do its best in fulfilling that intent for each and every visitor. To me, this is clearly a content negotiation issue and should not be solved in the form of verbose markup. Just because as designers we CAN always add markup, doesn't mean we should...not to mention the additional work of preparing multiple versions of the same image.