I wouldnt expect the park to throw in some expensive world class re-theming on an older ride that might not give them a great return on investment. The way I am thinking is that the park needed to replace its trains (afterall trains have a certain service life, yet trains are expensive). So like Six Flags did with Bizarro at SFNE, to help bring in some return on the new trains they needed, they attempted to retheme the ride in hopes of making it more marketable and basically help make some type of return on their investment (atleast to break even - but they didn't). In this case of the SLC... I can see the same. They are investing in track work and new trains so if they retheme it and give it a new look on a dime then they can possibly break even if not make profit on their investment. Superman was a completely new attraction so it made sense for them to go all out with the theme.
Leviathan - "I am a B&M, I am clearly not the father. I305 is not my child."
Millennium Force - "Yes he is Maury... I am 100% sure"
Maury - "Leviathan ..... in the case of possessed juvenile I305 .... you are not the father!
Maverick - (giggles with guilty grin)"