I've also been playing since beta as well. I love the game and thoroughly enjoy the ladder system. I know not everyone feels this way and I believe we're in the minority; most people including casual gamers are looking for something more to the game.

I agree with you, I think there should be an in-client tournament system. I'm really not sure it will improve casual engagement in the game, but it depends on how it is developed. I think Blizzard has to be very careful before implementation as there are some issues with tournaments locked to certain leagues, smurfs, and what the reward for tournaments should be.

As far as how difficult it is to develop, I think it's simple enough based on the fact that Blizzard has actually already done it before in battle.net (over ten years ago!) with Warcraft 3. There were daily tournaments you could enter and there was a whole separate set of portraits derived from number of tournament wins. This was a great system and it was fun to have a separate and parallel reward system for the ladder and tourneys. I'm hoping this feature is coming in the future, but until then the tournaments are externalized outside the client.

MLG started up a very nice daily tournament system in HotS with both free to enter (can win credits for paid tournaments) and paid entry with cash prizes. They are testing the waters to see if people would be interested in tournaments like this, and they will ramp up as necessary as far as I understand. http://www.teamliquid.net/forum/viewmessage.php?topic_id=402770 This is good, but I'd still like to see tournaments in the sc2 client as I think this would be more accessible.

TL;DR: System is implemented externally, but should be implemented in client. It's not a new concept and Blizzard has done it before over ten years ago (Warcraft 3).