Think about it Jurassic World has been a massive success (in-spite of some people's whining) largely because Jurassic Park is now a film people look back on Nostalgically. 20 years latter tends to be a common benchmark for that.
Well The Phantom Menace will be 20 years old in only four years.
I've personally been proclaiming it and other 1999 films what I'm most Nostalgic for for at least five years now. Since then as I've gotten even older what I look back on Nostalgically has expanded to include Episodes II and III, as well as all three LOTR films, hence why I loved experiencing The Hobbit movies so much in-spite of some of my complaints, most of which were purely about Desolation of Smaug.
Maybe that's why Disney is so determined not to have 3 years between films now. They don't want to be running SW off a purely OT Nostalgia based franchise to deep into the time Nostalgia for the Prequels will be jumping off. I think they are running a major risk burning out SW by having not even a year and a half between Episodes, and that's not including the spin offs.
Maybe once this Trilogy is done Disney is planning to do some Prequel based SW projects.
The people at Disney aren't complete idiots, I think it's unwise how they are catering to Prequel haters now, but there is a reason they're being subtle about it. I think they do know the Prequel fans are a massive market, maybe's they are just holding off on trying to tap that till they think the timing is just right.
If not, if they are really planning to keep this only the OT matters approach going indefinitely. It will still be past 2019 when Episode IX comes out. That is when I expect this lack of respect for Prequel fans could start really biting them.
But at any-rate as I said before the New Trilogy needs to bring more Nostalgia to the table if it wants to truly bring new life to Star Wars. Wouldn't matter which aspects of SW the Nostalgia is based on.
Update after seeing The Force Awakens, no spoilers.
The Movie was not like it's marketing, it embraced the Prequel and this person who feels Nostalgia for the Prequels felt this movie spoke to me just as much as the OT fans do.