Costco has some wacky high-end items every now and then that really drum up viral interest. They've sold 24k gold bars, high-carat diamonds, A5 wagyu, ibirico Jason, "economy-sized" bundles of premier cru Bordeaux, and quarter-million dollar Bosendorfers. The Yamaha piano events have always seemed to me to fall into this "somewhat luxury, somewhat whimsical, somewhat random" Costco-type thing to do, but I think it's also a very good thing.
I really like the Yamaha promotions, mainly because I suspect less than 5% of Costco shoppers have ever set foot in a piano store. So this is probably one of the best ways to expose today's consumer market to the fact that you can even buy an acoustic piano to learn on and have in your home.
I learned how to play piano when I was a kid, but I distinctly remember when I was at my last job, before I picked it back up as an adult, I literally had no idea that there were high end piano brands other than Steinway. It just never entered my mind and pianos aren't something that really come up day to day. Having Yamaha pianos at Costco seem like a huge net positive for the industry.