It sounds like you're mostly referring to UX. I share the impression that there's a lot of research in this area that rarely seems to be applied. One reason for that seems to be because people are lazy and/or too content with mediocrity. But the main reason seems to be just because it requires a lot of expertise. Which means either taking the time to train yourself, or pay others. Depending on your intent, this isn't always worth it (but I think people very much underestimate how "worth it" it is).