With 2000 gold I can buy mini expansion but you can't buy the same with 20 packs earned. Fuck that, you can't even enter in the arena with a pack and 50 gold. You need to play the game if you think the only thing gold can do is to buy packs, this isn't 2014 anymore.
Cards were in buckets based on their quality, yes, and how is it connected to balance?
So cards being in buckets specifically because of their WINRATE (not quality or whatever) is not connected to balance?
Cards with high wr were in the same bucket and these buckets had low frequency to show up during the draft. They did this so people won't draft 5 Flamestrikes of Mind Controls.