STAR WARS is as popular as ever, and will only get more popular in the coming years, but STAR TOURS, even with its fantastic upgrade, is still a small-scale attraction compared to the "real" thrills of ToT and RnRC. Simulators simply are not a big deal anymore, as you can ride them at your local mall now. It did not help that the attraction exterior was only changed slightly with the 2.0 refurbishment, so even people walking by the building for the first time in years may be unaware that something new is inside.
Disney is aware that they did a poor job of marketing the upgrade, such that they've been handing out little postcards advertising the ride at their gift shops.
The fanbase is huge and hungry for more experiences. They're older and they have kids and teens of their own. And right now, these fans don't have a place to play. STAR WARS needs a bigger, more elaborate footprint than just one attraction. It needs something real that guests can walk through, ride through, smell, taste and touch. STAR WARS is a world, a galaxy, not a corner outpost as it is represented now.