Quote from SK0L >>

I'm not totally opposed to a system like that. Letting the market decide a card's value instead of cards being lumped together depending on rarity. It gives it a physical TCG feel.
I mean, should Glacial Mysteries and Ultimate Infestation have the same value? It's up for debate. Artifact's system isn't really for me, but I can certainly see the appeal of it.

 The problem with "letting the market decide a card's value" is - some people will just play the market itself and pump up the prizes of cards one day and then - after a few days - they will drop so low that you will want to go cry in some dark corner. And that will happen A LOT. So, basically you will have to play shit tons of money to random "market players" if you want to build a competitive constructive decks all the time (ofc, Valve are getting their 5% rip off of every transaction) OR if you want to play the drafted (arena) modes, you will have to pay Valve shit tons of money since you basically can't go infinite on the event tickets. So, all in all - you have to put a lot of money all the time in to this game in order to be able to play it on somewhat Okay level. 

And about "getting the TCG feel" - you are wrong again. In Magic you have the physical object and it has a collector's value attached to it (even if the card itself is not used in the next expansion), which can't be compared to a bunch of pixels on your screen (and it's stupid for a bunch of pixels to cost $20 one day and $2 in one week, just cuz of a new patch/nerf/expansion).