I guess one of my main qualms with this, in addition to the fact that it weakens a bunch of interesting deck-building strategies, is that it's not very transparent or intuitive. How is the average user going to know that when he uses tribute, it's not increasing his chance of getting a rare? It's totally logical to assume, unless the card text says otherwise, that your chance of drawing any given card in a slot is the same whether that slot contained a card that you played, or a card that you discarded, or a card that was discarded by one of your or your opponent's cards.
If cards like auxilia, ice queen, relic hunter, etc. were too powerful (which... I didn't hear anyone saying they were), then I think it would have been better to change each of those cards directly (by increasing their cost, or changing the card effect), rather than making a confusing, non-intuitive change to the game's mechanics.