Reading through r/sleepheadphones, it's apparent that this market is extremely underserved. I blame China. By which I mean outsourcing manufacturing to a place with a lower standard of living, which makes it uneconomic to manufacture hardware unless you can sell millions of units or at very high prices that a) are unlikely to be commensurate with the quality (looking at you SleepPhones, which apparently only last a year despite costing an arm and a leg) and b) are way more than people have been conditioned to expect to pay.
It's weird to think about inexpensive manufacture making it so some products don't come to market at all, but that really is how it works. In exchange we get products coming to market that have no business being there. Specifically all the disposable electronic junk that can't be recycled, isn't worth repairing or refurbishing, and is poisoning our planet.