This is why I actually like the idea. While, yes, a Romani actor in the role would have been preferable, within the context of the multiverse, Secret Wars, and Battleworld as source materIal for Doom and the sudden need to switch up the villain, introducing a face EVERYONE in the Prime (616) universe knows as the quintessential good guy as a new villain jumpstarts so many character moments without any need for “backstory.” That backstory already exists.
And, really, there aren’t a ton of differences between Tony Stark and Doom on paper. The biggest difference is Doom’s mysticism, which can be learned depending on the backstory they give him.