Agreed.I know the difference, I think we tend to blow things out of proportion, this being one of those times. Will it be viable? Probably. Will it change the way you perceive Magic Kingdom as a whole? Probably not.
Does Rock'in Roller Coaster ruin DHS for you?
Some things need complete theming.
FoP wouldn't work in Pandora for instance as an unthemed show building.
But seeing part of a building in Tommorowland?
Doesn't bother me any more than RnR like you said.