As far as I can tell from the videos I’ve seen of them, they’re designed for carrying overweight, middle aged men, across beaches slowly.
If you live in somewhere which regularly gets a lot of snow then yeah, they make total sense. Over here though… 😕
Don’t get me wrong, if I won the lottery, I’d probably have one (in addition to the dozens of other bikes I’d have.) However until that happens, I really couldn’t justify one myself.