It's a feature if you are in the buisness of selling software to end users that need or want that, but that isn't the customer base of mainframe programmers or

It's a feature if you are in the buisness of selling software to end users that need or want that, but that isn't the customer base of mainframe programmers or similar kinds of deep backend work. If all your customers care about is that the paperwork crunching and adding up the numbers gets done right and on time every day (and after that, as cheaply as possible) then it's actively counterproductive to spend resources on a nice frontend. I don't think anybody is implying that there is no market for frontend engineering, just that resources spent on frontend are necessarily resources not spent elsewhere, and that different teams naturally have different priorities.