I'm going on the assumption that a business/forum almost never ends up being exactly like the owner first imagined it. Having an idea that involves the public and then actually exposing that idea to the public are two entirely different experiences. One is characterized by conception, the other by evolution. Preventing your business or forum from evolving is essentially handing it a death sentence. If you don't like that idea, you have two choices: allow it to evolve or hand it over to someone else who appreciates what it has become.
So I thought it might be interesting to find out from you forum owners: How did you first imagine your forum/site, and how did it evolve in ways you had not anticipated?