It's all about whether they can sell enough to make it worth doing. I was buying 116, 616, 620 and 828 long after all cameras that took those sizes were out of production. But I only used the cameras occasionally, and that's the issue. So I could understand it when they went- I was glad they were around as long as they were. Lots of companies (especially these days) do not support old products even if they could do it without losing money. They don't want to bother with it.
There are numerous threads here on APUG about respooling 120 onto 620 cores, easily found through using the search box. Some people have even modified 620 cameras to take 120 film, which would probably vary a lot in difficulty depending on the camera model.