10. Pacing
NXT TV, the weekly program which airs on the WWE Network, is merely one hour long and while main roster fans may be used to 2-3 hour formatted shows (Raw has been at least two hours since 1997 and Smackdown since its inception in 1999) the hourly format has a hidden benefit - it causes fans to always want more of the show when it ends, not less.
Contrast this less-is-more philosophy with the main rosters relatively bloated NFL-length presentation and it's clear that the pacing for NXT works. A one hour show prevents talent from being overworked or overexposed because competing in one or two matches (taped in a single day and aired over a month, as opposed to wrestling live every single week) guards the NXT faithful against growing tired of a specific wrestler.
It also means overly long, drawn out promo segments and constant replays can't happen and storyline build-ups can be done at an incremental place, encouraging people to tune over the medium to long-term.