If I wanted to be generous (I don't), I'd say it's because they want to scrap Gunn's project. Realistically, we all know your comment is the real reason. John Stewart's popular, but always gets shifted to the side (he's not the only lantern to have that issue when you have a bazillion greens, but aside from maybe Jessica Cruz, he's the only popular one to get shafted).
I do think the Gunn DC universe stuff was overrated, so I'm not surprised they're out. I enjoyed Lanterns, but didn't like returning to an era where the hero can't even wear his costume.
This merger is so painful for me. DC comics were on a roll, and now they're going to tear the whole thing down, again. If they're killing Lanterns, then at this rate they might just hire DiDio and Dixon back to make DC great again.