Can we just assume that Dracula looks different now because... wait for it... he changed his look? Maybe he got bored? He presumably didn't look exactly like this in the 1400s, and since he's not just an ordinary vampire (enhanced with the blood of Varnae and the spells of the Darkhold cult, according to Wikipedia), maybe that could account for the non-clothing aspects of his "new look." (Does this one get me a No-Prize? Regardless, would this work as an explanaton?)