a real demand for washers this big
Sadly yes,
While the federal government and others are pushing front loaders onto Americans, many by and large have not changed laundry habits to resemble say Europeans who have had decades of experience. The idea of a "small" or "compact" 5kg/11lb washing machine is a horror to the majority of American laundry market. They are used to saving up the wash for days, or weeks on end, then dumping the lot into a top loader. Worse the long cycles for front loaders (which have grown even longer as energy restrictions have changed), means they will wait to get though wash day.
Oh and despite they probably will wash their duvet on average once per year many Americans insist on washing machines able to handle "commercial" or "bulky" loads.
Results for these large sort of machines on average have been less than thrilling. Many shake and or vibrate horribly mainly due to unbalanced loads. The loads are usually unbalanced because the 15lb capacity washer has problems dealing with the five or less pounds of laundry it is has to wash. This or you hear complaints about units taking ages to balance/distribute a load and or simply giving up and not spinning fully at all.