Many of the reasons for wanting a hall-effect keyboard are reasons I wouldn't want one, others I find no value in. I feel like the only people who would enjoy a hall effect keyboard are people using the tactile-less cherry red switches, which is only small fraction of keyboard users
If the tactile feedback both existed and was adjustable, and didn't cost more than like 5-10% over a mechanical switch, it might take off more. But for now as neat as it is, it feels extremely niche. If someone wants different activation pressures and distances, they can buy different mechanical switches and would be missing out on basically nothing.