I'm sure the girls want to play. Whether or not the administration wants to take a chance on losing a couple matches, is only speculation.
But the fact is, they were awarded the B1G championship without having to play 2 of the top 3 teams in the conference; and the team they did play (Minnesota, in only one of their 2 scheduled matches) was missing their starting setter and libero (and they still went 4 sets).
Sure, they LOOK like the top team in the country, but we have incomplete data. NU and OhSU didn't get the chance to play them. It would be like awarding the football national championship to the Buckeyes before the CFP even started.