Why?

[Merlin]

Its not just that. This is supposed to be a professional website where people can find information on Final Fantasy and other RPGs without having to worry if a porn pop-up or genitalia-shot will show up in a sig while they are looking around.

You are free to create NSFW topics that are clearly labeled as such (and follow the rules). Opening such a topic is "at your own risk". OTOH, things like avatars and sigs are across the whole bulletin board and can be seen by people who are not expecting giant ascii "rockets" that fill up the whole screen or anime girls feeling themselves up in your avatars. I myself have had to change my sig because of the rules(specifically the one I have now), so I know it might seem a bit much at times, but it is for a good purpose.

I believe you will find similar if not more stringent rules on sites sponsored by game companies. The staff here is pretty lenient in comparison to the multitude of gaming sites I've been to, so I think this frustration is misplaced.