Yes conditioning is extremely important. It is one of these easiest things you can do to ensure the safety of all involved. When a body is out of condition it is much more prone to injury, it also means that you can ensure all participants have a good basic level of fitness. If you can't get through a conditioning session how can you expect to get through 2.30 minutes on the mat!
All my cheerleaders condition at every class and they have conditioning sheets that they have to work through during the week at home.