One idea would be to have multiple levels:
One for New Ideas, one for Highly Rated Ideas, one for Poorly Rated Ideas, etc.
Also, it would be good to include a voting system on the Card Idea forum, so that ratings for each card could be added to the spreadsheet. That way they can be sorted by Name, Element, Type, or Rating.
Bad cards should not be excluded, I think, because even from bad ideas can a good card be made... ideas would need to be sifted through to weed out or tie together those ideas that are very closely related to each other...