Parkinson said he thought it was to do with the transition in the level of rugby at that age; at under-14 level scrums become contestable, by half a metre, and lineouts have lifting in them.
He said part of the problem lay with parents who coached being scared off once the contact was upped.
"What that [contestable contact] does is scare off dads from coaching. What we want to do is focus on that group this year. We want to put a mass focus on them [coaches from under-14 through to under-19] this year and really get around with our rugby development team and work with them for them to become better coaches and actually stay in the game."
The NRU will continue to offer season passes to all players under-13 after the gesture went down a hit with young players.
This year, the NRU will be handing out between 5000-6000 free season passes to players and coaches.
On top of the free passes, Parkinson and the NRU will chaperone coaches to a barbecue at NRU headquarters and then on to a home ITM Cup match.
"We really want to stay in touch with those guys [age-grade coaches] throughout September-February and work with them so they can keep their teams together and in the game so they can keep their teams together for next year."