I am obviously talking to a wall here, but at least I tried. It is not the same as Trading Cards, I am actually a big fan of Card Games. You did not buy the bundle hoping for a chance at getting Goth Annie, did you? Card shops both sell card packs and single cards for those who were only looking for that card in particular, for those who bought many packs, and want the card they didn't obtain, but already have enough of the common and uncommon, and maybe some rares, but they want that one rare that is special to them, a card they love the art and lore behind. The card shop thankfully sells that card at it's value that is both agreed by the vendor and the buyer. In fact, comparing it to card games would be an argument in favor of releasing Goth Annie as a stand alone skin.
But continuing on that line, yes, a card shop will sell a rare card at its perceived value (usually 500-1000% of what a regular card is worth). Goth annie is available now for 4x what a regular skin is, and you get a bunch of champs/runes for free to boot!. Your point now? Ah, your point is, you want the skin that others paid a premium for, for a discount. Try getting a rare card for a discount because "you own every other one in the bundle"