At least you can find most of the 4 and 3 A brackets so you can count the entries.... Not always true with the other classes. However, I bet this is because the regionals up North don't want the ones down South to see.
But, regardless, I see no reason to change things. The lack of full or near full brackets speaks to something else - participation appears down. As success creates participation I see no reason to change the format and make it harder for kids to have success.
And, a 2 day regional will always be tougher when you have to watch weight and still wrestle. Good practice for state.
Of course I agree with seeing no reason to change things.
The two weigh ins is one of the things that makes a 2 day tournament tougher but I will remind you that one of the things that makes a 1 day tournament tougher is tougher competition. Of course many of the 5A and 6A wrestlers are very familiar with both, that is 2 day tournaments with really tough competition (Basehor, Newton, GC, Derby, Rosehill, etc).
6 of 1, half a dozen of the other? There are a lot of different variables that close minded people don't consider when they are hacking on 5A and 6A.