In the past we covered, then we didn't, then we did, then we didn't. Why?
Well, if you use the camper over the ice and snow months (like we did), then putting on and taking off that cover when it's covered with snow and ice is a very hard job. After the first time removing and it laden down with ice, and then you get it off the camper, and then figure out where to put it to dry out, well ... too much work.
So, those winters we planned the week of Christmas to Florida or South Carolina, we did not cover. Those years we stayed home all winter (Indiana), we covered. ..... until ... the RV simply got too long. Now at 41 feet long, we don't cover any more. BUT ... we also winter camp now too. Covering is just way too much in zero degree weather and 6 inches of snow on the ground and on the roof already!
If you plan on using the camper over the winter months, it's a LOT of work. If planning to store the camper only, covering is a good thing.