The problem with this argument is that we don't actually know what they are going to do creatively with the character, other than that they cast RDJ to play him and that he's going to be the villain for the next two Avengers movies. That is basically it. Everything else is rumor and speculation, all of which we should not put a lot of stock in at the moment. The final product is ultimately what matters.
In a vacuum, an actor of RDJ's caliber is a great choice for Doom. He's an Oscar winning character actor. He is charismatic as **** and has a ton of screen presence. Those are qualities I want in the actor playing Doctor Doom and Downey has them.
So it seems to me most of this outcry is just a heightened version of other castings that have had similar outcry in the past. People are taken aback because of the prior baggage the actor has playing another role and can't imagine this actor playing this character, and or they are upset that their personal fancast didn't get the role. This is just the latest and perhaps craziest version of that, in that an actor who played Iron Man for a decade and had an onscreen death is now coming back to play a different character. Its not the exact same baggage, but its still the same issue. "I can't see this actor playing this role because he played X" "I wanted someone else!" None of that **** is new in the long history of comic book movie castings. We've seen this song and dance before. Again... the final product is what matters.
And I am confused. Some of you were upset because you assumed he was coming back to play a Tony Stark variant, and that idea upset you. But now you are backtracking and wondering "why didn't he just come back as Superior Iron Man". Before it was "too safe" to bring him back as Iron Man, but now you want the safety and security of him being Tony Stark again in some form. So which is it?
Again... the final product is ultimately what matters.