What are the story behind these? I thought they were just a random community trend thing from a while ago, but the "Do collector cards still have value?" thread suggests otherwise.

They were valued back in 2012 etc, the purpose behind making them was probably for the enjoyment of having your tori on a card for players to collect.

They also seem to be from an event back in 2012 - LINK, that where it may have started

I have like 13 of them lol
U can trade them for some tc.
Some ppl still want them

http://forum.toribash.com/member.php?u=656740
Darkness made cards, I don't think he does anymore.
There is one as his avatar.

they were made for a promo-team event that failed. now they just exist for idiots to waste tc on them
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and i guess they also behave like textures so you can replace the original picture with w/e. i dont think they planned for them to work like that but shit happens

here's the original event thread. http://forum.toribash.com/showthread.php?t=126635

It would be cool if they were actually very cheap (as item) and you can get them by playing 500 or so games. Then, each time you beat someone that has a card, you gain it in your collection (not as item but as a trophy). Then ppl would actually be proud of their collections and try to collect more. If their collection would be shown on their user page as an album or something...
Market for them would be made than(ppl would probably hire artists just to make them those cards with their toris that look nice etc).
If the collection would have a value depending on the player's belt you manage to beat (higher belt, more value) then ppl would go around hunting for other players that have cards to incorporate them into their collections thus having a bragging right when gaining more valuable collections... idk