The case you outlined is not a matter of ugly UI but one of poor application design in general. It should be noted that a lot of those old grey text box UI’s do their job just fine. What is often most important for the data entry operators who use them is that they can navigate and fill in their form without having to take their hands off the keyboard to use the mouse which takes additional time and effort. What I often see in modernisation efforts to old enterprise apps is that they forget who their users are. The screens might look great with nice layouts and buttons but they aren’t optimised for keyboard only use and are actually a step backwards for the data entry operators who use them day-in and day-out.