You might believe that a patent should be written in clearly understood language, but if that were the case, I wouldn't be making the big bucks.
It is wise to write your patent so it encompasses as many variables and unknowns as you can get away with. Case in point, I once worked for a company that had a patent on a device that would fast wind a videocassette to a selected position and play from that point to another point. (patent number 4,224,644). It was useful for product presentations, interactive training, and video juke boxes. Panasonic tried to get away with doing the same thing, but they sued and got royalties.
Then came the video disk, and someone tried the same idea with it. They sued, but since the patent was explicitly written to cover video tape, it was not valid when applied against a video disk. The video disk had a major advantage over the tape when it came to accessing the location of the program quickly, and the enterprise folded, my job along with it.
If the patent had been written so it claimed a "video recording medium," which includes disks, instead of "video tape," they would be getting royalties from every DVD sold with a menu and chapters. And I would still be living in California, expecting a tidy retirement from a going concern.