Windshield wiper blades on most vehicles wear out and must be replaced every two or three years. However those used by the majority of motorhomes never reach the same worn state. Instead, they deteriorate from the constant exposure to the sun and from remaining in the same position for extended periods of time. Unlike your car, your RV may sit for weeks, or months, with the wipers inactive and the blades pressed to one side. These will soon fail to offer the performance you require for good visibility when they are needed.
First, not all wiper blades are the same. While some different designs may vary the price, the more expensive ones may very well work better in the RV application. The higher quality ones usually contain more UV protectant within their composition when manufactured. This may not be really worth it for your daily driver as they will probably wear out just as fast, but your recreational vehicle may be a different story.
Now, if your RV is going to be parked in one place for a period of time, whether in camp or storage, a little extra care can be employed. There are two items designed just for that; wiper covers and wiper stand-offs. The wiper covers are long bag-like protectant covers that slide down and cover the entire blade. This keeps harmful UV sun rays from damaging the blade material. Wiper stand-off blocks the wiper arm assembly enough to prevent the blade face from touching the glass of the windshield. This relaxes the wiping blade preventing it from becoming permanently bent in one direction. Both of these wiper saving items can be found at your local RV parts supplier. Alternatively, many people use a rubber ball with a slit cut in it to act as a stand-off, which works quite well.
So, pay a little extra for high quality wiper blades, add a bit of extra protection during extended stays, and enjoy a clear view when the weather turns bad. With a bit of preparation, life can be good.