One important factor is that folks who use SAP (or other enterprise software) get really good and fast at using it. Any changes to the UI and you have a major

One important factor is that folks who use SAP (or other enterprise software) get really good and fast at using it. Any changes to the UI and you have a major revolt on your hands. Not with SAP but having been a part of a project to modernize the UI an enterprise software solution, it usually isn't worth it. Users don't care about how it looks, they just want to get their jobs done as quickly and efficiently as possible. Any changes to what is displayed on what screen or location of buttons etc. causes a major disruption to the way they work.