Personally, I think its a big conspiracy among the equipment manufacturers. I believe that the reason sand filters are hardly EVER installed here is because they are so low maintenance. There's no stuff you have to regularly buy. You don't have to get new cartridges filters ever year. You don't have to get a replacement o-ring every 6 months because the POS stretched out. You don't have to get DE at the pool store all the time. You just backwash and get new sand (probably from home depot) every couple of years. Sand filters aren't profitable for them.
In my experience most homeowners are pretty lazy and could care less what type of filter was installed as long as its easy to work on. Whats easier than turning a valve?
What do you think TFP?
(BTW I'm only referring to residential pools here. It seems that DE is the norm with sand being second in the commercial world.)