While that is a good point, we routinely allow many non ubiquitous sources like dragon, the power books etc. This is wizard's business model - the more you buy, the more options you get. I dont really like it, but it is what it is.
I think the basic assumption here needs to be that everyone has access to all the books or the character builder, so feats etc are accessible.
Failing that, there are other online sources that have big lists of powers and descriptions of how they work.
I feel really bad about being "that guy", but if it's in the game, it should be in our game.
But on that note, I have no idea how we'd implement the cards that are coming.