It's not for everyone, but there are still huge crowds of people who want them and they have little to nothing to choose from. It's an untapped market and arguably it would be more profitable to target that market than a slightly wider market that is already over-saturated with similar selection.
It's weird that nobody makes a matte TV for rooms with lots of potential glare from common light sources like table lamps, overhead lights, the sun coming through your (hopefully) bright and airy living room.
Meanwhile, almost nobody makes glossy monitors. The last one I had was a 27" curved 120Hz Samsung thing from about 12-13 years ago and it had fantastic contrast but I actually wish it had been matte, given that the curve seemed to catch reflections from a wider angle behind me.
I suspect a lot of the reason monitors are matte is because in several major sales regions, glossy panels are illegal for employers to provide to employees for work in a typical office environment. Your employer in most of Europe, for example, has an obligation to reduce screen glare as part of their health and safety law. I doubt it's ever stringently enforced, but the fact that glossy monitors can't be sold to around half the potential customers in those regions because of government guidelines probably makes them harder to sell, driving a higher street price, which made them less appealing to buyers, so sales numbers worsened to the point that panel manufacturers just packed it in at stopped bothering.
It's also worth noting that glass-fronted touchscreens are often criticised by laptop reviewers around the world for being difficult to use in bright lighting or outdoors, and whilst they're usually praised for their rich contrast when watching movies, it never seems to be a net positive for review sites to have a glossy screen on a laptop.