I suspect part of the reason for making Casita 16s is that the Casita 17 is truly a heavy rig. For me to tow a Casita 17 would require a bigger tow vehicle.
Tow vehicle size and rising fuel costs have dramiticaly reduced the number of people on the road this year. The park we are in had it's overflow and boondocking
lots full at this time last year. This year there is no one in those spaces and still have a couple of normal slots empty.
The Thousand Trails campground near us has some empty slots and is advertising $200 a month specials.
I think the Casita 16 meets the need of people who don't need the extra height of the Scamp 16. Last year we had the opportunity to buy a 2005 Casita 17 for $7500 and turned it down because of its weight
and as a result we would have to get a new, larger tow vehicle. (We were towing a Casita 16 at the time.)
This year we'll be towing close to 12,000 miles and driving another 10,000 or so exploring and with rising fuel prices it becomes more of an issue. For this year's trip I am projecting 900 gallons at $4 a gallon for $3600 or about $300 a month.
A freind with a diesel truck driving back and forth to FL, some 5000 miles is projecting $2000. If he had done our trip he's be looking at $8-9000 or $7-800 a month.
Unfortunately most RVers have larger rigs making traveling less affordable. I believe there is a market for smaller, better organized RV's designed for long range travel.