Here's the problem, or, OK, two problems with your plan. One, the big schools would never, ever agree to it. Why would they? They aren't going to be in favor of expanding the tournament unless there is something in it for them. And creating 26 new bids for non-P6 schools isn't for them.
And two, the other people who won't be for that, even a little bit, is the people who are actually paying the money. You go to CBS and Turner with that plan and when they are done laughing at you they are going to tell you sure, you want to play all those extra games between Youngstown State and Howard, sure go right ahead. But they aren't paying you one dollar more for that. Because why would they? No one is watching those games.
If you want some evidence of that, back when they first expanded the field from 64 it didn't go to 68 with a first four, it was just one extra game. They played that game for a decade, and they were so memorable that pretty much no one even remembers that they happened. So when they added another auto bid, rather than just continue on with that and add another game between the bottom teams, the compromise to get the television people interested was four more at large bids, so that they could play two games between schools that people had heard of before in addition to the two games that no one cares about.