Just a guess with absolutely no evidence to back it up what so ever, but since Rita was one of the coasters built during the awkward transition between Tussauds and Merlin, when investments were low and they were bought out by some foreign investor, I think the lack of SW and general weirdness of Rita is simply down to a change of style internally brought on by higher ups wanting to put a signature on things. The fact that they reverted back stylistically after the Merlin buyout implies that the team of creatives involved were mostly the same before and after. The weird part is that Rita and the other weirdos (Stealth, Spinball and Fury) all did well for their respectful parks despite their lacking ...well, everything that seemingly made prior successes so important.
It's part of the reason why I'm still so skeptical of any claims that coasters (or anything for that matter) have to be innovative, or that the marketing has to be a certain way, or that the theme needs to be intense and narrative driven... No, it doesn't. Rita was abstract, small and insignificant in every imaginable way and the marketing frankly stupid, yet people still turned up in their masses to ride it.
I ****ing hate Rita, btw.