I just realized what those stats really mean. They measure the popularity according to post count.
Seems like "Card Ideas" is a forum section that not so many read. The reason why it's on top of the list is that a smaller group of people just post multiple times.
If you look at "view counts", which is a much better measurement of popularity, "Card Ideas" is nowhere near the top, therefore it doesn't really need its own section, which makes this thread useless.
Those suggestions you have are not bad ones, but my initial idea was to get all card related threads under "Cards". In my mind that's the best way because anytime you want to know something about cards, you just go to "Cards".
Makes sense, right?