I do have a real use case for it though: frequently I'm out on business trips, and the St. Louis airport is ~65 miles from me (with no charging stations in the lot I park in). There are many trips -- a monthly basis or so -- where I come home on a Friday morning, the family packs, and then we head out for a run to my in-laws' roughly 150 mi away. I'll be looking for new parking lot candidates - ones that might offer a charging station - over the next year or so, but I'm not aware of any.
Take away the high-speed charging need then consider the convenience. Will you need to carry your UMC with you to charge elsewhere? Frequently? Will you mind unplugging the 14-50 and coiling the cord neatly in the trunk/frunk on a daily basis (I have a 14-50 welder that's a BEAR to unplug), or would you keep the first UMC in the car and buy another UMC (rumored $500) to coil up and hang in the garage? In the end the price differential for another UMC vs. the HPWC is on the order of $700 - would you pay for double-speed charging for that $$?