As it stands, there is a new precedent with unranked ladder matches which I absolutely love, but consistently people point out that in Brood War plenty of people liked the game as spectators, but when they played themselves, did so in a much more casual manner, and unranked ladder is not going to remove as much stress from the game as casuals need.
The Arcade system is supposed to fill this void, and I like it more than most of the nay-sayers who have weighed in on it (could use some polish and tweaks sure) but I think that the Quick Match screen could have a little more too it.
Example: Some of the most common games I played in BW when I was younger, and before I got competitive, were The Hunters and BGH 3v3, 4v4 and 2v2v2v2, and these games modes differed drastically from regular 1v1 play in a lot of ways. Namely that they were fun cluster!@#$s where nobody maintained any disillusionment about balance, but enjoyed messing around with the units and mechanics of the game in a fun way. It generated respect for the pro scene and a casual learning about engagements and the game, it was fun, and it was still Starcraft. The spawn positions were hectic, random, and sometimes downright broken. The resources made different options for each race more or less viable, and nobody put any great deal of time into making sure this was fair or reasonable. Some days I would win 90% of my games with the same trick, other times I would be crushed and not understand why, but I was just happy to sit and wait for the game to start in a way that 1v1 has never replicated for me.
There are some cool BW mods, and BGH maps with dozens of campaign and editor only units currenctly in Starcraft 2, I like them, but the problems they sport are that they are too different from Starcraft, too unpopular, and that The Hunters is not an interesting map anymore considering how much the highground mechanic (and units who use and abuse it) and destructible debris have become prevalent in Starcraft 2.
Blizzard should add a subset of 3-4 different game modes that exist with the currents game balance/mechanics/unit set that are clearly casual and have them available right from the Quick Match screen. 3v3, 4v4, and to a lesser extent 2v2 are already games from which no reasonable balance can be attained that are played for fun, why not embrace it instead of maintain some silly attachment to "leagues". Make a new game mode, a Hunters, a map with 2-3 bases each for up to 8 people that have more resources than you'd expect to start with in a normal game, no shared or special spawn rules, and just let people go to war and play Starcraft as a game. (No, FFA does not fill this void, its boring and anti-social)
Maybe take some old BW units or the Blizzard Allstars Units and add in a Merc Compoud/Lurker Den/Some removed Protoss building as a hero builder and have a casual mode of SC with a hero unit that plays more like WC3 and you can play a 1v1, 2v2 or FFA of that.
If Blizzard All-Stars is going to be thrown into the game, why not put this in Quick Match along with these other options? Make Starcraft a game of games as it once was. This does not cheapen or draw any attention away from the pro scene, and I can assure you that almost all my casual friends would still be playing the game if these things were already in effect.
Fun or Not? Great idea to get some newer custom maps played, why not have a section that allows you to fire up a random custom right from this screen. Also, why not have all the Blizzard customs or Featured customs on this page as well?
Like the specific ideas or not, all I am saying is, add more functionality to the Quick Match screen. Every time I talk to my friends about SC2 they revert to talking about BGH being fun or how amazing it was when customs were clever out of sheer necessity due to the map makers limitations.
The first criticism I expect to see (aside from a few people starting with "this is stupid because <unconstructive ramblings and a nonsensical reference to plankton>") is that this screen may be too "busy" but with the combination of dropdown menus for subsections, or a clever tab section to simply expand it, I am sure there are plenty of great ways to handle it well. They literally make oversized buttons on it now to try and fill whitespace anywsay.
Commence crapping on my idea community! ^.^