I think the big takeaway here is the deliberate usage of the poster. Chewbaka is right. Every theatrical showing of STAR WARS since 1997 has used the rerelease poster in marketing materials and press packages. Plus one has to consider a certain upcoming landmark birthday year for the film.
The title is probably just a product of marketing/brand synergy/canonicity. STAR WARS has been A NEW HOPE for 35 years save for one afterthought DVD release in 2006.