The vast majority of the vans are not driven off road and also run the stock tire size.I am confused - why does anyone want wheel well liners on a truck ? We used to take them all off our OHV vehicles they were a PITA. Can't see why anyone would want them on a van either... usually the first thing we take off our off overland vehicles if they come with them... mostly because they interfere with larger tires .
In my experience these are some of the advantages of having wheel well liners:
The strong case to order wheel well liners
For your use, it is nice that they are optional since there is a cost saving of not including them as standard.