LMS Outages During Normal Semester

I am not entirely sure I understand the way that college and university IT departments justify their downtime. From the 8th of April until the 15th of April Gaston College is taking down their perfectly functioning Blackboard server to replace it with a “new” and “improved” version of Blackboard. We are a few weeks from the conclusion of the Spring semester and the 8th, 9th, 10th and 11th are normal class days. Why are we being interrupted for an unnecessary outage during scheduled class time?