was part of both the design and development teams for Magic 2011. If the Titans received the most time and effort during the process, then Leylines probably received the most worry. Why do you think that might be?
Before you clicked the mulligan button, you had an article that discussed how we want the game play of Magic to feel like it matters to the outcome. Imagine this card:
Leyline of Haste
If Leyline of Haste is in your opening hand, you may begin the game with it on the battlefield.
All creatures have Haste.
With this card, you are obviously supposed to make a little red creature deck. The problem with it is that the difference in power level between a game that begins with this card in play and a game that does not is enormous; even more so when the opponent doesn't have creatures that they're interested in attacking with early in the game. Some of Standard's fastest red decks can win a game unopposed on turn four, and with this card that could be cut to three easily. On the other hand, when you draw this card on turn two, it's a total blank. Many proactive Leyline designs we tried had this same effect on the game—they made the opening hand feel too important.
At first glance, the line of text that comes with the Leyline territory seems very difficult to use without this opening-hand-magnifying effect. However, we took our inspiration from the superstar of the first Leyline cycle...
... which we also decided to repeat ...
... and made Leylines that were reactive rather than proactive. By this, I mean that rather than helping you do something, they make it harder for your opponent to do certain things. Leyline of the Void plays the hero against degenerate graveyard strategies like Dredge, even in Vintage where Dredge decks have cards like Bazaar of Baghdad. Leyline of Punishment stops many of the white effects that traditionally vex red burn players. Leyline of Sanctity messes, in turn, with those same burn decks, and hurts combination decks that need to target you to win. Leyline of Anticipation messes with opponents who plan to use lots of countermagic against you.
In all cases, you might argue that these still increase the importance of the opening hand. In certain match-ups, they can, but this tends to happen when the deck on the receiving end of a Leyline is particularly non-interactive. Extended dredge decks in the past few Extended Pro Tour Qualifier seasons could easily win on turn three, and with a deck that fast sometimes only a Leyline can bring the two decks back into interaction. Similarly, a mono-red deck playing against a Circle of Protection: Red is hardly a game, but adding Leyline of Punishment into the mix gives a higher chance for an interactive game. Our goal with these Leylines was to increase the total interaction in Magic rather than decrease it.
You might also point out that Leyline of Vitality doesn't quite conform to the "reactive card" model. It does less of an obvious job than the other four Leylines in Magic 2011, but it still does that job at times. Just last Friday, I saw a red-green drafter with lots of one toughness creatures sideboard this in against a black drafter who showed multiple Stabbing Pains in the first game. He indeed got to start the third game with his Leyline in play, and that was the difference that allowed him to win his match. I was pleased to see that interaction.
Still want to try again? You'll get less content, but you can still ...