I agree, also after some random combinations people will get to like even more some decks, which are not so popular. For example, there is a tendency, where people love playing with Nature, Soldier, Holy and Mage decks, which lead to easy victory. Few are the people who play with Undead or Unliving or even fully Brigand decks. Also more experience can be gained this way (I don't mean the XP counters, but actual experience) since people will understand how different decks function. This will lead to more competing and intense games.
A variety in game modes is helpful, also to oppose Xpoh's remark that people tend to only play with Hidden Decks etc, I'll suggest to divide slots in a way so that people can play any kind of game. E.g. out of 13 slots in total, we can play 7 slots as Hidden, 6 slots as Non-Hidden and an extra 5 slots for friendly games (this is merely an example and not actual numbers I would like it to be, I prefer hidden games as it's more intense and strategic in a way, since you must guess what kind of cards your opponent has in hand by judging the way he's trying to save up particular resources, or by his/hers keywords).
At any rate, various game modes will help establish more fun and exciting ways to play this amazing game, and will also help people seek out new strategies, instead of stucking with old ones.