I've watched the shows where folks are looking for tiny houses. It's rare that they look at RVs there have been a few. The comments you hear when they look at an RV along with the tiny houses....the RVs look like RVs and the tiny houses look more like houses/cabins. Other than that I agree it's a fad thing... One couple chose the RV they looked at mostly because it was cheaper and they could tow it with their existing SUV. It was a Casita fiberglas TT.
Both my wife and I feel if more of them looked at a 5th wheel along with the tiny houses more would choose a 5th wheel. Especially those who plan to move it often.