It a idealistic thought; setting the weigh ins the morning of the fight will eliminate weight cutting.
It may reduce the size of the cut, but even if they set the weigh in an hour before, there will be cutting.
The issue with Chavez Jr. is not the size of his cut; but the legality of his cut.
Its true, Julio Jr. often comes in 25lbs heavier than opponents;
in and of itself there is nothing wrong there.
If you can do that healthily and legally more power to you.
But there are numerous questions over Chavez's cut and particularly pharmaceutical agents that may have been used.
He is not a Light heavyweight. With correct training and nutrition he would probably be a middleweight.
20lbs may sound a lot from a boxing perspective. It is.
But from a grappling perspective, that would be a regular cut.
Freestyle wrestlers; they have the real hellish cuts.
The problem is, in striking arts we expect and anticipate strikes to land to the head and surrounding areas. Without any scientific support I know that getting hit while you are dry hurts more than in your natural, well hydrated training state.
Selecting a weight class is your own choice and responsibility.
In boxing particularly there is a weight class every 5lbs or so.
More severe punitive measures for those missing weight will result in more careful consideration of what class you are truly capable of making.