I don't know if hung up on trackless vehicles is quite it, more that happenstance led them to building a lot at once. It was the correct choice for what they wanted to do with RotR, but has severe limitations as a thrilling ride vehicle. It was the correct choice for MMRR until they nerfed some of the utility of having a trackless vehicle in the design phase. Ratatouille was a "we have money to spend" off the shelf pick, and OLC would pay whatever for the BatB ride. Then you clone MMRR and you've got six in a small window of time.
I can't go on RotR without thinking of the Simpsons between the final Kylo scene and the escape pods:
Good explanation and even better visual demonstration. Maybe RotR involved "look like you belong there" type of sneaking.