To work well a join page needs to be clear and concise and convey trust. It doesn't need to be generic or not match the rest of the site in order to do this.
We see the plain join page thing a lot with our own pay site CMS customers. I believe a lot of people just throw up a join page and don't give a lot of thought to its importance in the sale process. I also believe a lot of people don't know where to begin when it comes to creating a solid page or optimizing this sort of stuff.
