I agree on the Surrender option, it would solve a lot of the leaving that's going on, And Leaving should count as a defeat in the leaderboards, even though they are glitched, some people are still playing for it.
Well in 2015 we'll have Booster Packs and custom decks in a limited pool, ain't that bad already. I ain't going on MTGO, because i play Paper Magic and i don't want to pay for virtual cards when i go the real thing in one of my boxes. But for a 10 bucks game, i think it'll be good :)

They could include an option to concede the game without leaving, as in playing a round of 1 on 1 best 2 of three games and conceding spares time when you want to move on to the next game.
One thing I find silly is that the AI takeover option from DotP2013 is not in Magic 2014. Being forced to play vs AI if you want to play it to the end because your opponent leaves is silly. It would be nice to have that "old" AI takeover option you can enable or disable at your own choice.

Personally i don't see a reason to leave, if he doesn't have any answer to your play, he will lose in 2 turns, so in my opinion it's not wasted time, especially if you can play several more games with the same person after that. it sucks that his deck only has one Path to Exile, which would be his only answer available.

.. and I sac Khalni Heart Expedition giving me 8 tapped forests in total at the end of turn 4. Turn 5 I cast Eldrazi Conscription and enchant my elf giving him +10/+10, trample and Annihilator 2. My opponent left the game when he saw Conscription, I don't blame him. ;)