Well some groups like to test a person's roleplay ability before letting them in. It can get annoying having the think of something to write, but it's the group's preference and their way of selecting members.
Well, RP samples are very common things from the groups adding in fluorite.
I've seen a lot more WC then wolf packs do it, though wolf packs do.
It's not really the annoying user, it's the fact they want to keep their RP clean of 'trolls' and/or illiterates.
RP samples are there so that members can have a 'full RP experience' (which I don't agree with).
Basically, RP samples are around because people don't want illiterates to use their illiterate magic to make some of their members leave.
Because apparently, a lot of literates leave their group if just one illiterate is there, even if it's on once in a blue moon.
It can be rather annoying sometimes, but I don't get what the big D is about them.
It's just a small RP post before you get into a world of literates.
It's like putting in a password before you enter a huge room filled with codes and such, just waiting to be tested and played with.
(Le Sorry for geeky example XD)
Personally, people that don't join a group when there's an RP sample make no sense.
I mean, it's just another RP post.
Though, I don't like 98% of RP Sample Judges, who don't give you ANYTHING to RP as.
I give my soon-to-be-members a mini-plot, the same every time:
You are walking through a forest in the middle of the night. The shadows of the long pines around you make this place more and more mysterious. There is a slight rain dripping through the leaves above.
^ My sample plot.
So, that's easy to follow, and can easily be used to form an RP sample.
So when leaders want you to make a RP post right off the bat, with nothing to build off of, asking for a small plot is good.
Anyways, to sum up what I said, 98% of Group Leaders are jerks and don't want their members running from a single illiterate if it gets in.
Rant: Over.