I don't think Spider-Man & Transformers are comparable to traditional dark rides. Most people probably go to theme parks expecting them to have several dark rides, based on Disney's model. It's such a basic, traditional form of ride that all they really need are different themes & effects to set them apart completely.
Likewise, most people aren't going to complain if a park/resort has more than one simulator, mainly because it's such a common ride system, although I personally do find them redundant.
Spider-Man & Transformers, on the other hand, use a more unique, very specific ride system that creates a pretty similar experience IMO. The fact that it's a screen-based attraction is largely to blame, as there aren't going to be as many practical effects to set them apart, unlike in dark rides. The fact that Transformers seems to purposely mimic Spider-Man in several places doesn't help either. If they were to build Transformers at UO, I would hope to see several key scenes changed to help differentiate the two.
Putting Transformers in USF would also create another redundancy problem -- it would be the park's 4th 3-D attraction. And let's assume they put it in SS44's place. That would put 3 of the 4 attractions directly across from each other, with another nearby. Seems like overkill to me.