Was thinking about this type of idea while discarding cards the other night. Current system: We get bigger decks, which hold more spells, sideboard, copies, etc. But we still only draw the same amount of cards as we did at level 1 (seven I think). So as we move along in levels we are forced to keep our decks as small as possible, negating any benefit we get with larger decks. Many level 70s still run around with a tiny deck for efficiency.
So why not have your amount of cards increase when your level does?
I am not sure of the coding and whether it would/could/should be tied to the deck or to the player's level, but it would let us take advantage of the vast array of spells in the game. Right now, I keep a minimum deck with almost nothing fancy (death has alot of possibly useful spells that take up space) due to only drawing a set number of cards. Too many spells in a deck makes it a mess if you want an efficient fight.