The feature has helped make the class A's a bit more family friendly regarding sleeping arrangements. Common class A saying, entertainment for 6, dinner for 4, sleeping for 2, was pretty much correct other than the sofa or bunk models. Pop up towables had more matress sqft than a class A. There are even a few DP models with the bunk. If you see a newer DP with the door someplace than in front of the front wheel it probably, but not always, has the drop down bunk.
For prospective owners take into consideration that there could be weight limitations of the bunk. Makes a bed for a couple of kids but two adults might be pushing it's limits.