I'm rather surprised Jester doesn't make the cut.
Well, if you're taking the existing bots, that's probably why - several of these cards are optimized play for that card, and they'd need to be re-optimized for reality with Jack. And several aren't optimized and just buy one of said card, and need to be re-optimized for reality with Jack.
Yeah, straight double Jack is darned strong, but there's lots of other stuff that adds to it - just, it doesn't add THAT much to it.
Well, the list isn't that authoritative, it's just to give an idea of how many $5 cards can work with Jack. I'm not sure about Jester. You can try to optimize it, but really it doesn't do anything exciting here. Most of the time, you're going to hit silver or copper, neither of which is going to change too much, so you're kind of just taking a terminal silver.
And I'm not sure what you mean by "it doesn't add THAT much". Most of these (completely unoptimized) bots are 10-20% favorites over double Jack.