They released Trinity in stores and I will be a very pissed person if they don't release it in stores. I like having the game physically in my hands to so I can install and uninstall as I see fit.
The thing about having hard copies on store shelves is that it's always possible that people who have never heard of the game before might see it and be intrigued. It's being visible for sale is a form of advertising, and it raises the game's profile. The cover should say "Game of the Year winner" conspicuously to increase people's curiosity.