The pre-Deathwing Neltharion model complete with body ruptures and metallic jaw/plates is just laugh-out-loud ridiculous.
I know that this might be a bit tough to swallow for some, but the use of the current Deathwing model in that scene was a matter of efficiency. A ton of work went into 4.3, and we squeezed in as much as we could, but it didn't make sense to dedicate the huge resources it takes to create a custom model for that one cameo, and we were concerned that using a generic black dragon model wouldn't have the same immediate value of recognition.