I feel like I should start out by saying that, at least on oldGuild, "two paragraphs minimum" was the [i]Advanced[/i] standard, not Casual. Casual was "one paragraph minimum", and the member base sort of turned it into something different when people who didn't want to play in Advanced but still wrote at Advanced standards stayed in Casual. The site has no specific "requirements" for the sections now (not that they meant much on oldGuild, anyway), so the three sections really only represent what people collectively want them to represent.

In general, though, I've noticed people from Free [i]and[/i] Advanced tend to cling more to Casual even when they would better fit in said other sections, and this is probably due to activity levels. Casual is by far the most active, and so people whose RPing preferences are sort of borderline will generally gravitate towards Casual so they can run and participate in RP's with higher activity levels. Even I'm sort of guilty of this. Personally I care little about the lengths of people's posts and will join a thread in any section so long as I like the idea. So, when I GM, I almost always place my RP's in Casual, just because they'll get the most attention there. *shrugs*

Though, following this logic, I'm sure there are a lot of other Casual RP's with standards closer to what you'd expect to find in Advanced. Due to this phenomenon, Casual has always been the section with the most variety. In Free, people generally expect very short posts, and they'll find a lot of those. In Advanced, people generally expect longer posts, and they'll get a lot of those, too. in Casual, who knows? You have some threads where standards are a bit lower, some threads where the standards are a bit higher, and some that really do reach the "middle ground" you're looking for. But, since there's [i]so much[/i] going on in Casual, I'm sure you'll find a thread with standards to your liking before long.

Or, failing that, you could always make an RP and set your own standards about post lengths. The Free/Casual/Advanced division only really exists to group like-minded RPers together; there's nothing stopping you from setting your own standards that don't perfectly conform to the expectations in any one section, especially since said expectations are even more meaningless now than they ever were. :hehe