Part of what makes me ehh about the complaints about farming arena is the rewards to the risk. Gold is worth something like 115-130 per win, and the decks are weaker than a FG, not to mention that you lose less electrum when you lose as well. Granted, it takes a better deck to streak through Arena than it does FGs, but that's more because the FGs are set in stone and easier to analyze. I feel like beating an FG should net you a larger Electrum reward. Now that said, if it would be bad to make FGs more profitable to farm electrumwise, maybe instead you could get a 'special' spin when you beat them after the normal spins. This would balance the difficulty of FGs out with the rewards in Arena.
That said, earlier today I think I EM'ed the 2nd place deck in silver and got like 1280 electrum from it. Though the person who had it up there had neglected the thing and let it go to 1 HP if I remember correctly...