Also, here's a quick comparison for you regarding the average score of top 2 teams from the different regions, since we're talking about regional balance at NXN. I'll leave out the Southeast, because for the first half decade of the regional era that region was simply pretty far behind and there's no way to reasonable balance it against the rest of the nation (and I don't think it's behind anymore -- it is admirably deep even beyond the AQ teams).
Average boys scores of Top-2 teams by region as it stands:
210.54 Southwest
240.04 California
250.13 Midwest
259.13 Northwest
279.29 New York
281.08 Northeast
325.67 Heartland
320.08 South
Average boys scores of Top-2 teams by region using the 7-region layout I mentioned:
202.13 Northwest
234.92 Midwest
238.75 Southwest
261.36 Mid-Atlantic (missing 2 teams, so they would likely average more like 280 with the full 24).
265.00 Northeast
266.79 South
... that is WAY more balanced.
Average girls scores of Top-2 teams by region as it stands:
150.67 New York
253.21 California
257.46 Southwest
269.96 Midwest
318.80 Heartland
323.96 Northwest
375.71 Northeast
376.48 South
Average girls scores of Top-2 teams by the 7-region layout I mentioned:
149.71 Northeast
235.00 Southwest
236.04 Midwest
259.58 South
292.83 Northwest
312.92 Mid-Atlantic
... again, that is WAY more balanced.
And I already did a quick look at what teams would no longer have been able to qualify for NXN, and there are only really two teams of note. The only significant minimum losses were mostly on the girls side from over a decade ago, and it seems the nation has become MUCH more balanced since that time.
Here are the only four teams that scored under 400 points that would no longer have made the field:
2007 Warwick Valley NY girls (#11 at 301 points)
2008 Lincoln-Sudbury MA girls (#14 at 307 points)
2009 Arcadia CA boys (#20 at 373 points)
2015 Neuqua Valley IL boys (#19 at 381 points)
Meanwhile, all the regionals would be tougher than they have been aside from the Southeast (though without Footlocker drawing away athletes, and a closer location to the bulk of the region, the region might be a little stronger to mitigate the loss of states to the new Mid-Atlantic).
Combining New York with the New England states, and California with Nevada/Arizona, would only make the NXN field stronger. It doesn't punish California and New York for being so good (those states will continue to send teams as long as they are good enough to make it), but instead strengthens regions that aren't as deep and don't always have multiple potential Top-15 type teams.