This reason has been brought to the staffs attention many times in the past. Getting to make the next challenge is not much of a reward and can be punishment for some. As for the challenge rewards, there may be some actual 'fuss" that is not being vocalized.........coming up with challenges has been very hard. It almost doesn't feel like a 'reward' for being the winner, lol! So I am liking the idea of set themes. Concerning challenge rewards, I don't think anyone is particularly fussed, are they? The peer recognition is nice as it stands.
Paraphrasing a PM I received awhile back from a core member on this particular subject, "I come to PSG for other reasons, I don't participate in challenges because there are other sites on the net that focus on contests exclusively. They offer much better rewards for the winners. There's simply no incentive to participate here."
I'm also in favor of Hoogles suggestion of not confining the challenges and opening up artistic expression.
On another note and a reminder, this thread has been viewed by only 12 members at the time of this posting. There are 19 members online, 13 of those have not even viewed this thread.