The "publicity stunt to move digital" hypothesis doesn't make a single bit of sense.
They had 2 million rentals/purchases in the first 3 to 4 days, which they made $15 million on. That's fucking AWFUL for a movie with this amount of hype. "Neighbors", another Seth Rogen comedy with a fraction of the publicity, did $50 million in its opening weekend earlier this year.
Just translating that 2 million number to theaters, at an average of $10 a ticket, that's 25% more in revenue.
The kicker is that each of those purchases/rentals is paying for 2 to 10+ people to see the movie -- and multiple times -- whereas a ticket is just one person.
And the people who see it in theaters don't own the movie. If they want to watch it a second time or show it to a friend, they have to pay again, whether in theaters or once it's released on DVD, etc.
Plus, the theaters don't take a cut first week and only get small percentages from then on. They make most of their money on concessions.
Then consider that the movie was downloaded illegally AT LEAST 50%
more than it was downloaded legally. I'd estimate it was closer to 100 to 200%, at about 4 to 6 million illegal downloads.
That's fucking HUGE. Releasing movies digitally guarantees that a quality rip will be available to pirates day 1, as opposed to now, where some movies don't even have quality copies until the movie hits DVD, and it's still very rare at release.
With this movie, everybody who wants to see it will already own it a month or two from now, whereas it would possibly still be in theaters the other way. So after the movie had already made more money in theaters, it hits the DVD/digital market, where it makes even more money on top of that.
Not to mention the hit to the international market they'd take by going completely digital. You think people in most non-Western countries are going to pay you $15 to download something online?
If this movie didn't have this impossible to replicate publicity, the digital release would have been a complete and total disaster. Not to mention the other Sony movies the pirates leaked or the lawsuits filed against them.