I just had to add these back this morning. I redid 4.5.0.44 this morning to remove all the Quincy/RIM Internal Tools stuff.. Following JC's memory cleaning guide once again I removed all the Dimension themes except for Icon.
When it rebooted my screen looked like an old Mac classic. black and white crappy icons.
Selecting any theme did absolutely nothing when I clicked the trackball to activate it.

Tried reinstalling the wallpapers but that didnt do it. Finally worked when I put the remainder of the Dimension themes back on it. Noticing the Zen theme was almost 2MB, Im guessing RIM's got something in there that has to do with more than just the theme selected at the moment..