I think this is yet another indication of the relative infancy of the sport. Participants have gotten involved with one race or another for all sorts of reasons. Friends, family, work...casually running across something on the Internet. And whatever race they start with becomes their go-to race. Now, people are starting to wonder what else is out there and whether those other races are something they would be interested in doing. After all, how many times can you really do the same race in the same place? Something I have asked myself a number of times.
In the end, I suppose that's the purpose of my writing, To help people see what these races have to offer and provide some info to help them decide what other races might be worthwhile. And yes, there are definitely differences between races...even between different venues within the same race. In the end though, what I've found so far is that when you look for the reasons why people are doing OCR, the harder you look, the less difference you really see.