Started GMing Cardinal Rift a few months ago. We've got 12 players, and, personally, I'm ecstatic with the amount of diversity. Each character feels unique, we've got different backstories, origins, etc.

One thing that I'm really proud about is how I believe CR's diversity was brought about by the setting my coGM and I created. We wanted to make a world where anyone could play any sort of character they wanted. One of the principal character traits was magic. Our magic system is very limiting, and yet open at the same time. By giving people the chance to explore the boundaries of what magic can or can't do, I think we sort of brought about creativity in other aspects of character creation.

Of course, magic isn't all of it. Personality is big too. By making a world with very different areas and backgrounds, we let everyone really expand what they liked.

Sorry if it was a bit of a ramble. I suppose my end conclusion is that the setting itself is often what fosters character diversity. If the GM makes a world where there's options, the players will take those options. To answer the bit about through different RPs, I really don't know. I haven't been on the guild long enough to say.