Have you ever purchased and downloaded a game, only to then have to download several hundred megabytes more just to play it, and then found it doesn't even work with your HTC EVO or other device? By the time you can download 300MB of additional game data, your 15-minute return window has passed you by.
Google's looking to change this.
In the past applications on the Market could be no larger than 50MB, with any additional data having to be downloaded from third-party servers contracted or run by the developer. This meant that even if the Market was up, the extra content could be down due to fire, floods, earthquakes, tornado, power outage, or beer spill.
Now Google has plans to let Android developers store up to 4GB worth of extra data in the Market, and users will not start their 15-minute window until all the data has been downloaded.
It will be interesting to see what app developers do with this multi-gigabyte storage improvement. Now that you don't have to worry about sideloading and hosting content and dealing with justifiably annoyed customers, we may be seeing the dawn of the Very Large Application. Users will also not be hit with gigabyte shock when they download an application they think is 22MB and it turns out to be 400 (I'm looking at you Captain America).[Android Developers Blog]