To me getting a jade relic should be like christmas, special. I have a pretty average Temple, level 8. If I did the math right I have about a 0.11% chance of getting a specific jade relice reward after any given encounter. In my guild we typically do 2 levels a week, occasionally 3 if someone ponies up the higher level goods. So on average I should get ~1.8 of each jade relic per year assuming real life doesn't cause me to miss any expeditions. So it really should be special.
As far as making some sort of proposal I do not know what would replace it. I would assume that would be part of any formal proposal. It seems that what was once really rare, store buildings, 1 up and renno kits, are not so rare any more. I was trying to come up with ideas they could use or modify to make a new rare item. I had a few general thoughts but I don't know how hard they would be to do. Any other ideas would be welcome.