Combining input and output randomness
The input randomness I sometimes appreciate in TTRPGs is when I can roll up a character. Especially for the lighter TTRPGs in which you can quickly roll up a character and it's okay if they get killed I can roll another. That input randomness can lead to creativity both in how to make sense of the story of the character (why do they have these combination of attributes) and how to play them (how to leverage their attributes). A life path generator is sometimes an even better implementation of this.
The research paper you linked was also very interesting. Thanks for sharing!
This would be an interesting experiment to see on a larger scale with a western population. Wonder if things like culture, gaming experience, ages etc. effect the conclusions and would the same conclusion happen with a different context like a cooperative boardgame vs a competitive TCG. Cool to think about!