I can see the benefit of a deck like this:
First, you can open your camper door and let the toddler or dog out onto the enclosed deck while you fix lunch, etc.
Second, if there was a major rainstorm and the ground is a swamp, you can still sit outside.
Third, with the raised deck, you can have a better view of the lake, ocean, etc.
Fourth, you have a covered space to store firewood, etc, while camped.
Is it something everyone wants or needs? No. But is it something that will cater only to people who "want to be in nature, without being in nature"? No.