Which in turn would clash with the current scripting that only allows one deck at a time.
Next you'll argue that they should create the possibility of saving multiple decks at once to different game rooms.
Right now, since you can only play in one room there just isn't a reason to keep that many 'active decks'. And you can save the presets already and the dropdown menu is right there with the game client. That's as fast way to change between decks as you need unless they for some weird reason do follow through on your idea.