Good point. I agree that "auto-theming" (to use David Younger's terminology from Theme Park Design) is almost never optimal, and I would almost never want it for a new attraction that's being built from scratch, but...
I find it to work much better for RnRC than the DHS version, because at least it's believable (plus the "light show" on the ride itself is a really cool concept). I think the vehicles themselves (obvious roller coaster trains), and the boarding and launch areas (with visible track), make it basically impossible for the "limo" version to ever be believable. It should also be noted that the WDSP version's premise - a recoding studio in LA that built a roller coaster in collaboration with musicians - remains a thematic premise (rather than being an amusement-park-y lack of theme, though again, I still agree that "auto-theming" is suboptimal).