Digital Distribution could very well be the thing that saves the Video Game industry. Look at us now. All we have are God of War clones and Gears of War clones. Everything is so extremely derivative. 99% of the games out there are all about how cool it is to blow someones head apart.
Why? Because these are the games that have proven to be profitable. You can make money with them. With game budgets getting huger and huger, you have to guarantee a return on investment or else you'll end up with a huge debt.
There's another side to that as well, these huge games set new standards which kind of take other games further, make them better. Look at Shenmue, that game introduced Quick Time Events. Now, some say damn them to hell for this but you can't deny that QTEs are a good way to immerse you in a game or keep you on your toes. I remember dying after the Del Lago boss in Resident Evil 4 because I thought it was over when the cutscene played but obviously it wasn't

Most of the games nowadays have some form of QTE. Or the cover system form Gears Of War, the free form climbing from Prince Of Persia, the regenerating health instead of using med packs. All these things were introduced in AAA games. I mean, look at Uncharted for the PS3, this game is basically a mix of Prince of Persia and Gears of War in an Tomb Raider/Indiana Jones kind of setting, and it's great. Mirrors Edge was very daring in my eyes and felt incredibly fresh and new and that WAS a big budget title.
And honestly just as I like to watch a Michael Bay or James Cameron blockbuster in the theater, on the big screen, in all its glory, I like to play games like the God Of Wars and Call Of Dutys and Gears of Wars of our time, which push technical limits and help take the experience one step further.
How do you solve this? By reducing the barriers to getting a product out there. It's a lot easier to get creative products to make a profit if you don't have to worry about over-producing physical copies, don't have to worry about manufacturing packaging and discs, etc.
It's why some of the best games we have seen this gen have been on Steam, on PSN, on XBLA, and on WiiWare. Those are the only places where you are allowed to be creative. I'll take AudioSurf, PixelJunk Monsters, Castle Crashers and World of Goo over most of the shlock that gets sold for $40-60 any day of the week.
10 years ago, I would have thought that making a video game and making money off of it was nothing but a distant dream. These days, it's possible. A few years from now, the likelihood is only going to get better.
The thing with the download-only games you mention here is that they are indeed very creative and great games, but they simply don't offer the content to justify a $40-$50 price tag. I totally agree that these platforms (XboxLive, PSN and WiiWare) are a perfect breeding ground for new and fresh ideas. Where small developers who might not get the chance to share their vision and game with other people otherwise can shine.
BUT... honestly, would you buy Castle Crashers for $40 or even $30? It's an awesome game but the target audience for that game is small, the game is short and very simplistic. So for a game like Castle Crashers, World Of Goo or Braid digital distribution is the right way to go. Like you said, you don't have to manufacture a CD, packaging, a manual, you don't have storage costs for storing pallets full of boxes with the game and so on. These costs bear no proportion to the potential revenue. By releasing it as a download only game they bypass all this, the only costs are the licensing costs they pay to Microsoft, Sony and/or Nintendo to be able to put the game on XboxLive, PSN or WiiWare. This way the loss of earnings is bearable should the game bomb or it is very profitable if it does well and may open some doors for bigger projects for the developers.
What we are talking about here on the other hand is digital distribution for
FULL PRICE games. Games that are or were available on PSP on the UMD format. So by your definition this is only WORSE because they not only offer PSPminis (potentially creative games in the vain of PixelJunk Monsters) but they offer you the Metal Gear Solids, The God Of Wars and all the other "derivative" games. But it gets even worse from here, potential DRM. You payed full price for a downloaded game, and THEY tell you how you can use it, share it, play it. When, after years, your PSPGo breaks, and your downloads are gone, will you be able to re-download them? What if they pull the plug on the servers when they move on to the next generation or unplug it for good because they changed their business model. Your games are lost, you can't chase them down on eBay and buy them again, there's nothing to put on eBay in the first place! Like someone mentioned earlier, Sony is in complete control over the things YOU buy. There are no price cuts out of necessity (unsold games that take up space in their warehouses), they lower the price only when/if THEY want it, and not when the market demands it. So is all the money you spent down the drain? Will there be a refund? Or say, when you are late to the party, and you buy the PSPGo when it already began its decent. When no one cares about it anymore but you're somehow interested in it. The servers are down or they dropped certain games from their catalogue. How do you get them? Imagine the SNES were all about digital distribution. Now, years after its gone you want to buy one for old times sake or to get the games you were always interested in. You see this awesome game, Chrono Trigger, you want it but you simply CAN'T get it. It's gone, for good. You can hope for a compilation disc down the line or a remake but this version is gone, deleted. I'm sure there is some faulty logic in my remarks here, but this is how I see it and these are all points that worry me.
From a technical point of view I don't see us switching to digital distribution for the next 10 to 15 years. I can't imagine that the "digital infrastructure" evolves that much in just a short time period to make games that fill a BluRay disc readily available to everyone. You don't "just" download 20+ Gigs of data. So as the games and graphics evolve, digital distribution of AAA titles will be even harder than it is already. But from a game collectors point of view, someone who loves looking at his collection and hunt down games he wanted to play all the time, I
DESPISE digital distribution for everything but the "small" arcade games we have right now. Truth be told, the day, should it ever come, all new games are only released as a download is the day I'll quit buying (then)current generation games!