Most NCAA championships are single-elimination. Further, baseball doesn't have the cross-over, only softball. Softball games are short enough that they can usually get 4 in a single day (edit: so the 8-team WCWS can have all teams "in synch" in the way that the 8-team MCWS can't; cross-over isn't a whole day advantage or disadvantage, depending on bracket side) & player fatigue isn't a big consideration, except for pitchers.
As I recall baseball did it for a year or two and did away with the crossover. As to why softball--no idea. Just to be different? And try to add some excitement to something already exciting?
How would you feel about playing #1 Seed Texas today, and again on Monday? Plus, I'd guess ESPN prefers as many different matchups as possible as the tournament progresses.
It’s pick your poison between Texas and Oklahoma this year. Keegan and Ava have to be at their very bests and bats must go inferno.