Exactly- some RPers see R or 3-3-3 as sex! everywhere! w00t! but higher ratings does not exclusively mean sexual themes. I'm much more interested in dark atmospheres/tones/whichever, than in the occasional sexytimes between a pair.
There are many forum games that cross the line, and so there's graphic TOS-breaking content all over the place, but sooner or later they get shut down. Sadly, a lot of forum players are fixated on the look of the site. After all, there's bloody Forum of the Month awards, and so many other contests for graphics.
I've been a member/staff of a few forum games in which the staff cared about the writing, but there's more games that favor graphics over writing. I enjoy making graphics for boards, but I completely understand why some get turned off by it: minimalist designs work best for everyone, but people just can't not... participate in the contests. Or in general, show off with huge graphics.