I am not exactly poor, I have around 60k between all my characters, but I am picky about what I use it on since it covers more stuff. Do I want to put a whole set of green gear for that alt that I will only use for two levels, or do I want to buy that Scorpion Mount, or those really expensive jewel-crafting mounts, or maybe that 100k Yak. Do I want to hit the AH and blow 5000g on that epic bracer that I would likely upgrade with VP or LFR? Or do I want to hit the pet store and buy pets to complete my collection?
With JP, I don't have to make that choice. I get both currency from running dungeons, so I save one for my gear and the other for my "extras".