Disney builds very short rides now. Both of the Avatar rides are less than 5 minutes. For no real reason. Once the new wears off, FoP will have a shorter line, and could easily deliver for 6 minutes, while only increasing cycle time about 20%. And increasing budget almost insignificantly.
NRJ was just budget cheapness. Adding 2 more minutes would have increased budget quite a bit, but really, adding 2 more areas would make it much more rerideable.
Many people are Gaga over Journey to the Center of the Earth, very similar to NRJ, but with actual thrills A slow ride past amazing scenery, then a huge, incredible animatron. But then it is followed by thrills. It's very good. But if it had two more caverns and a secondary AA, I would consider it absolutely incredible.
Disney, especially WDW, is in "just enough" mode now. Add a cool coaster to TSL. Wait, that's too cool, this smaller version is good enough to keep people in line.