Of course you don't think so! I mean, you are you, right? Just like people that write in free verse have trouble understanding why anyone would choose to write a villanelle. After all, you can write anything you want in free verse, but there are formal constraints with other forms.
Where is the FUN in that?
But perhaps your fun isn't the fun of other people. There are other real people talking to you here. I'm one of them. If I tell you, "I, a real person, find my fun and creativity in limitations and constraints," then doesn't that mean something? If a person says, "I know I can write any type of book, but I want to work within this genre convention because I enjoy these formal limits and I find it exciting and refreshing to explore the bounds of creativity within a structured setting," then who are you, or me, to gainsay that?
To move back to the instant example- yes. I think that there are many, many people (some of them on this thread) that find additional "creativity" and "fun" in working within specified rules. For those people, the idea that race and class is just "whatever," isn't freeing- quite the contrary. It's anathema to creativity.
From my perspective, the whole point of playing a half-orc wizard would be that if I choose to do so, it would be precisely because I was playing
against type. Because there were mechanical limitations that I was working within and around- to me, that is the creative process. But it's fine and good if that's not you.
Different strokes for different folks. You can write free verse- just don't demand that everyone else write their poetry the same way.