Being able to predict the weather and issue waivers really isn't going to change the stats. There may be a few people who can fly out a day early or a day late, but it's not going to be the majority of travelers trying to get someplace.
Weather related delays accounted for a third of one percent of all United Flights in May, and less than half of all their delays.
In May, United had 1,535 out of 426,375 flights delayed by weather (according to the government stats). Even if every single person on every one of those flights were offered a waiver and took another flight it would have very little impact on the final numbers.