Not just programmers. AutoCAD has had this kind of interface always, and it is absolutely the best/fastest way for power users to make drawings. Integrating nicely textual commands, prompts and mouse usage works very well there.
Looking at proficient Excel users (I always claimed if my ex-wife got a basic course in operating systems principles, she would write one in Excel in a week :) = they tend to do everything by keyboard, and not in terms of shortcuts or chords, but entering commands. I also worked in a printing shop, and people working in layout program such as InDesign all day, would do everything by keyboard also - entering coordinates, align constraints, style names - and they were only slowed down by having to navigate all those little input boxes.
I also worked for a couple of years editing video in non-linear editing programs (Media 100, Premiere), and boy does this work get repetitive at times. I would have loved to have the ability to do things programmatically.
So, I think any power user could benefit from a command line driven interface in applications like those. Photoshop, non-linear video editing, computer aided design, layout, word processing, and even web browsing - I could see this option used by all kinds of people.
