To me, when you're releasing a movie called Episode VII and five out of the previous six movies in the series were financed by the company you just purchased to make it, wouldn't you want to proudly roll out those other movies again?
This isn't like when they intentionally held off on a blu-ray release of the original Tron (even pulling unsold dvd's from the shelves) because they were afraid of people seeing it and not wanting to buy tickets to Tron: Legacy. This is Star Wars we're talking about here. The new movie is banking on people's nostalgia. If not an OOT release, I would think they'd at least want to do a 3D theatrical release of the SE prior to Episode 7's arrival.