I feel like we've discussed this a couple of times, but how could the ladder be better?
If they give arbitrary divisions like other games with elo ("silver", "gold", etc.) then you'd A) get people being elitist by dismissing others as "silver trash" or whatever (maybe this already happens with numbers but I don't know), and B) you'd have either elo inflation from locked-in divisions, or the same results because your rank is just masked.
In addition, having larger divisions would make the game feel more grindy because you have to play even more games before your number ticks over (this happens in League of Legends for example). If there's a buffer to prevent rank dropping, then the game likewise becomes more grindy. Note that people can try decks in casual, but presumably the meta might be different there so the argument is that it's not the same. People can easily experiment with decks now even in ranked. They might quickly drop a few divisions, but by the streak mechanic they will also very quickly regain ranks if they find a successful deck.
I can see the mana curve argument though.