Yes, photos of Star Wars, Episode VII will benefit from being leaked to the public. That is just what today's society is craving, and that is what will make Star Wars, Episode VII even more popular and intriguing. The public needs to see glimpses in order to be enticed to go and see the movie.
Hollywood has known for a long time the power of the teaser trailer in creating a sense of buzz and excitment about upcoming blockbusters. In the age of social media, what better way to create buzz than to leak photos and let discussion between fans commence and let the word spread. It's practically free marketing and spoils none of the plot (or very little at least). It's win/win for the companies and the audience.
The leaking of star wars photos is good for both sides as it engages both of them. From the fans perspective they can imagine what will become of thier beloved movie franchise and water cooler talk about it. For the movie maker side it drums up much hype about the franchise reboot.
Yes, photos of Star Wars, Episode VII should be leaked to the public, because it would be good advertising for Episode VII. People who are fans of Star Wars cannot get enough of it. It would be good promotion and it would build some hype for the next episode, which people are looking forward to.