I'll offer a concept for restructuring. I'm sure many of these ideals have already been talked about.
1) Have the D2 division end at regionals and crown a regional champ for D2. If a team is still trying to grow, it still gives them some kind of season ending goal. You will still have a few teams that are skilled enough for D1 playing in D2, but after regionals, the talk about those teams are over and everyone will concentrate on the National bound teams.
I counted at least 30 teams out of the 77 currently playing D2 that would likely move up and there may be more.
2) There are 38 teams in the D1 division this season and 24 are headed to National, along with 16 D2 teams. After regionals, rank the teams in D1 and send the top 16 to Nationals under a "tier 1" level and the next 24 under "tier 2" level. NCRHA will have the same number of teams going to Nationals and tiered divisions would be much more competitive. Plus, those teams on the bubble will have extra incentive to get into the tier they are wanting or get a bid period.
It is just an opinion and I don't know all the ins and outs to getting it done, but it doesn't seem that difficult.