I guess it also depends how you use your RV. I would imagine if we full-timed or even spent half the year in mild climates and out of the intense summer sun, I wouldn't worry about covering ours. However, since we don't do that, our RV might sit for a combined total of several months baking in our extreme heat.
The cover is indeed a complete pain to put on as our coach is 42'. That said, considering our financial investment in the RV I would argue that the hassle of covering it is very reasonable. I spend about 45 minutes covering it and about 15 minutes removing the cover. When I pull the cover off, I leave it rolled up nicely on the RV pad.