In a recent interview with Edge, Sony representatives have revealed the company's rationale behind supporting both physical and downloadable releases on the upcoming PlayStation Vita. In short: size matters.
SCE Worldwide Studios president Shuhei Yoshida said that while may people might be ready to embrace downloadable gaming, an uneven infrastructure means that "Some PS Vita titles, like Uncharted: Golden Abyss, will be close to 4GB in size, which could be too large to download for consumers 
who do not have a fast broadband connection."
While it's comforting to know that Golden Abyss will be a meaty game, Yoshida is right that such robust experiences complicate the downloadable model, even when Internet access isn't an issue. With the Vita's lack of onboard storage and relatively high-cost memory cards, downloading large titles would be a noticeable inconvenience. The largest card available, at 32 GB, would only be able to store eight games of Uncharted's size, and would set you back at least $100 on top of the digital purchase price.
There's also the matter of personal preference. "Some consumers like shopping in retail stores, talking to knowledgeable store clerks, buying and playing games on the spot," Yoshida added. "We do not want to remove that capability from consumers.”
The PlayStation Vita is scheduled to launch in Japan on December 17, with the handheld hitting the rest of the world sometime in 2012.