I work on several pieces of business software at my job. One was built for UNIX mainframes, almost entirely in C, with the end-users still capable of running on

I work on several pieces of business software at my job. One was built for UNIX mainframes, almost entirely in C, with the end-users still capable of running on dumb terminals (or these days a PuTTY window). The "successor" runs on Windows servers with J2EE, a GUI, and all the modern niceties. The most common complaint I hear from people who've switched from the legacy software to the modern one is that their end-users' productivity is greatly reduced by the point-and-click interface. The older software's TUI had a very steep learning curve, but almost like learning Vim, once they developed a muscle memory for the necessary keystrokes, they could access and update information much more quickly.