I'm not advocating cutting ornamental grasses down in the fall, unless they are some of the messy miscanthus. Ornamental grasses are generally quite beautiful in the winter because of their upright form and sometimes foliage color. The other reason we might cut some down is placement. Sometimes they are along sidewalks or drives and when heavy snow falls, they hang over the walks or can contribute to drifting issues along drives. And yes, I have been guilty of installing them too close to sidewalks.