It’s not because they didn’t want to, or didn’t know but that retailers have size and weight limitations for shelf space. You also have to net the retailer more margin the more shelf space you take up, so even 10, and 12” models were too expensive. Not to mention the larger and heavier the more customers you scare off. Perfect Storm...
That said, some of these have ways around it. Klipsch has a large enough footprint that they can offer a 15 that you might not see in stores. SVS went the opposite direction by gradually inching up price and squeezing into BestBuy show rooms.