The recent discussion around rotation, combined with a few recent comments from friends who play this game, inspired me to share a few thoughts on why I believe a more robust use of the restricted list would be the better option. I have posted a somewhat lengthy article on CardGameDB that explores each of the many aspects related to this issue, including card design, power creep, and what the composition of the restricted list might look like. The article is available here: http://www.cardgamedb.com/index.php/index.html/_/articles/an-argument-for-more-frequent-use-of-the-restri-r126 . (No login required to read.)
For those who prefer the shortened version, my basic argument is this: Each card set includes a small number of cards that are slightly too powerful, a small number of nearly worthless cards, and a majority of cards that are more or less balanced. In the competitive environment, good players typically tend to use more of the better cards and fewer of the mediocre cards. Ultimately, the mediocre cards become virtually unplayable because they cannot compete. The "real" competitive card pool is thus comprised of a much smaller number of "top-level" cards that are used much more frequently. Unsurprisingly, these cards typically do not mirror a particular theme, such as Tullys or dothraki, and they tend to be less thematic than less competitive builds that focus on flavor (such as a build based around dragons). Rotation, whereby older cards are excluded from legal competitive play, would do little to rebalance the environment because (1) many of the most powerful cards are relatively new, and (2) rotation would simply reduce the number of powerful cards while also eliminating many cards that are perfectly fine. Sure there would be fewer overpowered cards in the environment, but overpowered cards would still exist and see a lot of play. The only sustainable way to deal with overpowered cards and slow power creep is to use the restricted list much more frequently or liberally than it is currently used.
I expect there will be much disagreement on this conclusion, and I welcome comments and suggestions. I think this discussion will ultimately help FFG decide on a path. The decision makers tend to be somewhat attuned to public opinion, and players here have much to contribute.
If you do disagree with me, I would request that you at least take a look and skim through the longer article posted on CardGameDB. It may be that I have poorly represented my thoughts in short form here. I have vetted the longer version, and it does a good job (I believe) of laying out in logical fashion why a restricted list would be the best course of action, compared with rotation and/or in-game balancing through the printing of more cards.